Custom Element Basics

Custom elements are defined with StacheElement. The following defines a <my-counter> widget and includes it in the page:

<!-- Adds the custom element to the page -->
<my-counter></my-counter>

<script type="module">
import { StacheElement } from "can";

// Extend StacheElement to define a custom element
class Counter extends StacheElement {
    // The HTML content within the custom element.
    //  - {{ this.count }} is a `stache` magic tag.
    //  - `on:click` is a `stache` event binding.
    // Read the VIEWS section below for more details. 👀
    static view = `
        Count: <span>{{ this.count }}</span>
        <button on:click="this.increment()">+1</button>
    `;

    // Defines the properties used in the view of this custom element.
    // Read the OBSERVABLES section below for more details. 👀
    static props = {
        count: 0
    };

    increment() {
        this.count++;
    }
}

// The name of the custom element
customElements.define("my-counter", Counter);
</script>

An element's:

• properties are defined with the Observables APIs documented below.
• view is defined with the Views APIs documented below.

Also, the Element Bindings section shows how to pass data between components.

Observables

Define custom observable key-value types with ObservableObject. ObservableObject is used to organize the logic of both your StacheElement props and your Data Models. The logic is expressed as properties and methods.

The following defines a Todo type with numerous property behaviors and a toggleComplete method.

import { ObservableObject, ObservableArray, type } from "can";

// -------------------------------
// Define an observable Owner type:
// -------------------------------
class Owner extends ObservableObject {
  static props = {
    first: String,
    last: String
  };
}

// -------------------------------
// Define an observable Todo type:
// -------------------------------
class Todo extends ObservableObject {
    static props = {
        // `id` is a Number
        // and uniquely identifies instances of this type.
        id: { type: Number, identity: true },

        // `complete` is a Boolean and defaults to `false`.
        complete: {
            type: Boolean,
            default: false
        },

        // `dueDate` is a Date
        dueDate: Date,

        // `isDueWithin24Hours` property returns if the `.dueDate`
        // is in the next 24 hrs. This is a computed property.
        get isDueWithin24Hours() {
            let msLeft = this.dueDate - new Date();
            return msLeft >= 0 && msLeft <= 24 * 60 * 60 * 1000;
        },

        // `name` is a String.
        name: String,

        // `nameChangeCount` increments when `name` changes.
        nameChangeCount: {
            value({ listenTo, resolve }) {
                let count = resolve(0);
                listenTo("name", () => {
                    resolve(++count);
                });
            }
        },

        // Owner is a custom ObservableObject with a first and
        // last property. Whenever `owner` is set, the value
        // will be converted to the Owner type.
        owner: type.convert(Owner),

        // `tags` is an observable array of items that
        // defaults to including "new"
        tags: {
            get default() {
                return new ObservableArray(["new"]);
            }
        },
    };

    // `toggleComplete` is a method
    toggleComplete() {
        this.complete = !this.complete;
    }
}

// -----------------------------------------------------------
// Create and use instances of the observable key-value type:
// -----------------------------------------------------------

// Create a todo instance:
const todo = new Todo({ name: "Learn Observables" });

// Change a property:
todo.dueDate = new Date(new Date().getTime() + 1000 * 60 * 60);

// Listen to changes
todo.listenTo("nameChangeCount", ({ value }) => {
    console.log(value); //-> 1
});

let handler = ({ value }) => {
    console.log(value); //-> "Learn observables"
};
todo.listenTo("name", handler);

todo.name = "Learn observables";

// Stop listening to changes
todo.stopListening("name", handler);

// Stop listening to all registered handlers
todo.stopListening();

// Call a method
todo.toggleComplete();
console.log(todo.complete); //-> true

// Assign properties
todo.assign({
    owner: {
        first: "Justin",
        last: "Meyer"
    }
});

// Serialize to a plain JavaScript object
console.log(todo.serialize()); //-> {
//      complete: true,
//      dueDate: Date,
//      name: "Learn observables",
//      owner: { first: "Justin", last: "Meyer" },
//      tags: ["new"]
// }

Define observable list types with ObservableArray:

import { ObservableArray, type } from "can";
import Todo from "//canjs.com/demos/api/todo.mjs";

// -----------------------------------
// Define an observable TodoList type:
// -----------------------------------
class TodoList extends ObservableArray {
    // Specify the behavior of items in the TodoList
    static items = type.convert(Todo);

    // Create a computed `complete` property
    get complete() {
        // Filter all complete todos
        return this.filter({ complete: true });
    }
}

// -----------------------------------
// Create and use instances of observable list types:
// -----------------------------------

/// Create a todo list
const todos = new TodoList([
    { id: 1, name: "learn observable lists" },
    new Todo({ id: 2, name: "mow lawn", complete: true })
]);

// Read the length and access items
console.log(todos.length); //-> 2
console.log(todos[0]); //-> Todo { id: 1, name: "learn observable lists" }

// Read properties
console.log(todos.complete); //-> TodoList[Todo{ id: 2, name: "mow lawn", complete: true }]

// Listen for changes:
// TODO
todos.listenTo("length", ({ value }) => {
    console.log(value); //-> 1
});

// Make changes:
todos.pop();

// Call non-mutating methods
const areSomeComplete = todos.some((todo) => {
    return todo.complete === true;
});
console.log(areSomeComplete); //-> false

const fullName = new Observation(() => {
    return person.first + " " + person.last;
});

Views

Render a template that updates the page when any data changes using can-stache:

import { stache } from "can";
import Todo from "//canjs.com/demos/api/todo.mjs";

// Create a template / view
let view = stache(`<p>I need to {{ this.name }}</p>`);

const todo = new Todo({ name: "learn views" });

// Render the template into document fragment
let fragment = view(todo);

// Insert fragment in the page
document.body.appendChild(fragment);

Common can-stache tags and built in helpers:

<p>{{ this.value }}</p>

{ value: "<b>esc</b>" }

<p>&gt;b&lt;esc&gt;/b&lt;</p>

<p>{{{ this.value }}}</p>

{ value: "<b>unescape</b>" }

<p><b>unescape</b></p>

<p>
  {{# if(this.value) }}
    Hi
  {{ else }}
    Bye
  {{/ if }}
</p>

{ value: true }

<p>

     Hi  

</p>

<p>
  {{# if(this.promise.isPending) }}
    Pending
  {{/ if }}
  {{# if(this.promise.isRejected) }}
    Rejected {{ promise.reason }}
  {{/ if }}
  {{# if(this.promise.isResolved) }}
    Resolved {{ promise.value }}
  {{/ if }}
</p>

{
  promise:
    Promise.resolve("Yo")
}

<p>

     Resolved Yo

</p>

<ul>
  {{# for(todo of this.todos) }}
    <li>
      {{ todo.name }}-{{ this.owner }}
    </li>
  {{/ for }}
</ul>

{
  todos: [
    { name: "lawn" },
    { name: "dishes" }
  ],
  owner: "Justin"
}

<ul>
  <li>
    lawn-Justin  
  <li>
  <li>
    dishes-Justin  
  <li>
</ul>

<ul>
  {{# for(todo of todos) }}
    <li> ... </li>
  {{ else }}
    <li>No todos</li>
  {{/ for }}
</ul>

{
  todos: [],
  owner: "Justin"
}

<ul>

  <li>No todos</li>

</ul>

<p>
  {{# eq(this.value, 22) }}
    YES
  {{ else }}
    NO
  {{/ eq }}
</p>

{
  value: 22
}

<p>

     YES  

</p>

<p>
  {{ let first = this.value.first }}
  {{ first }} {{ this.value.last }}
</p>

{
  value: {
    first: "Bohdi",
    last: "Meyer"
  }
}

<p>

     Bohdi Meyer  

</p>

<stache-examples></stache-examples>

<script type="module">
    import { StacheElement } from "can";

    // Extend StacheElement to define a custom element
    class StacheExamples extends StacheElement {
        static view = `
            <p>{{ this.escapeValue }}</p>
            <p>\{{{ this.unescapeValue }}}</p>
            <p>
                {{# if(this.truthyValue) }}
                    Hi
                {{ else }}
                    Bye
                {{/ if }}
            </p>
            <p>
                {{# if(this.promise.isPending) }}
                    Pending
                {{/ if }}
                {{# if(this.promise.isRejected) }}
                    Rejected {{ this.promise.reason }}
                {{/ if }}
                {{# if(this.promise.isResolved) }}
                    Resolved {{ this.promise.value }}
                {{/ if }}
            </p>
            <ul>
                {{# for(todo of this.todos) }}
                    <li>
                        {{ todo.name }}-{{ this.owner.first }}
                    </li>
                {{/ for }}
            </ul>
            <p>
                {{# eq(this.eqValue, 22) }}
                    YES
                {{ else }}
                    NO
                {{/ eq }}
            </p>
            <p>
                {{ let first = this.owner.first }}
                {{ first }} {{ this.owner.last }}
            </p>
        `;
        static props = {
            escapeValue: "<b>esc</b>",
            unescapeValue: "<b>unescape</b>",
            truthyValue: true,
            promise: {
                get default() {
                    return Promise.resolve("Yo");
                }
            },
            todos: {
                get default() {
                    return [{ name: "lawn" }, { name: "dishes" }];
                }
            },
            owner: {
                get default() {
                    return {
                        first: "Bohdi",
                        last: "Meyer"
                    };
                }
            },
            eqValue: 22
        };
    }

    customElements.define("stache-examples", StacheExamples);
</script>

Common can-stache expressions:

<p>{{ [key] }}</p>

{
  key: "age",
  age: 3
}

<p>3</p>

<p>{{ add(age, 2) }}</p>

{
  add(v1, v2){
    return v1+v2;
  },
  age: 3
}

<p>5</p>

<p>{{ add(v1=age v2=2) }}</p>

{
  add(vals){
    return vals.v1+vals.v2;
  },
  age: 3
}

<p>5</p>

<stache-examples></stache-examples>

<script type="module">
import { StacheElement } from "can";

// Extend StacheElement to define a custom element
class StacheExamples extends StacheElement {
    static view = `
        <p>{{ [key] }}</p>
        <p>{{ addArgs(age, 2) }}</p>
        <p>{{ addProps(v1=age v2=2) }}</p>
    `;
    static props = {
        age: 3,
        key: "age",
        addArgs(v1, v2) {
            return v1 + v2;
        },
        addProps(vals) {
            return vals.v1 + vals.v2;
        }
    };
}

customElements.define("stache-examples", StacheExamples);
</script>

Element Bindings

Listen to events on elements, read data, write data, or cross-bind data on elements with can-stache-bindings:

<input value:from='todo.name'/>

todo.on("name", () => {
  input.value = todo.name;
});

<input value:to='todo.name'/>

input.addEventListener("change", () => {
  todo.name = input.value;
});

<input on:input:value:to='todo.name'/>

input.addEventListener("input", () => {
  todo.name = input.value;
});

<input value:bind='name'/>

todo.on("name", () => {
  input.value = todo.name;
});
input.addEventListener("change", () => {
  todo.name = input.value;
});

<input on:change='todo.method()'/>

input.onchange = todo.method;

<button on:click='todo.priority = 1'>
  Critical
</button>

button.addEventListener("click", () => {
  todo.priority = 1;
});

<div on:name:by:todo='this.shake(scope.element)'/>

todo.on("name", () => {
    this.shake(div);
});

<stache-examples></stache-examples>
<style>
.shake {
    /* Start the shake animation and make the animation last for 0.5 seconds */
    animation: shake 0.5s;
}
@keyframes shake {
    0% { transform: translate(1px, 1px) rotate(0deg); }
    10% { transform: translate(-1px, -2px) rotate(-1deg); }
    20% { transform: translate(-3px, 0px) rotate(1deg); }
    30% { transform: translate(3px, 2px) rotate(0deg); }
    40% { transform: translate(1px, -1px) rotate(1deg); }
    50% { transform: translate(-1px, 2px) rotate(-1deg); }
    60% { transform: translate(-3px, 1px) rotate(0deg); }
    70% { transform: translate(3px, 1px) rotate(-1deg); }
    80% { transform: translate(-1px, -1px) rotate(1deg); }
    90% { transform: translate(1px, 2px) rotate(0deg); }
    100% { transform: translate(1px, -2px) rotate(-1deg); }
}
</style>
<script type="module">
import { StacheElement, ObservableObject } from "can";

// Extend StacheElement to define a custom element
class StacheExamples extends StacheElement {
    static view = `
        <p>Updates when the todo's name changes:
            <input value:from='this.todo.name'/>
        </p>
        <p>Updates the todo's name when the input's <code>change</code> event fires:
            <input value:to='this.todo.name'/>
        </p>
        <p>Updates the todo's name when the input's <code>input</code> event fires:
            <input on:input:value:to='this.todo.name'/>
        </p>
        <p>Updates when the todo's name changes and update the
            todo's name when the input's <code>change</code> event fires:
            <input value:bind='this.todo.name'/>
        </p>
        <p>Calls the todo's <code>sayHi</code> method when the button
           is clicked:
            <button on:click="this.todo.sayHi()">Say Hi</button>
        </p>
        <p>Animate the div when the todo's <code>name</code> event fires:
            <div on:name:by:todo='this.shake(scope.element)'
                on:animationend='this.removeShake(scope.element)'>
                {{ this.todo.name }}
            </div>
        </p>
    `;

    static props = {
        sayHi() {
            console.log("the element says hi");
        },
        shake(element) {
            element.classList.add("shake");
        },
        removeShake(element) {
            element.classList.remove("shake");
        },
        todo: {
            get default() {
                return new ObservableObject({
                    name: "",
                    sayHi() {
                        console.log("the todo says hi");
                    }
                });
            }
        }
    };
}

customElements.define("stache-examples", StacheExamples);
</script>

Custom Element Bindings

Similar to the bindings on normal elements in the previous section — you can listen to events on custom elements, read, write or cross-bind an element’s properties with can-stache-bindings.

The following shows examples of passing data to and from the <my-counter> element in the Custom Elements Basics section:

<!-- Listens to when count changes and passes the value to doSomething -->
<my-counter on:count="this.doSomething(scope.element.count)"></my-counter>

<!-- Starts counting at 3 -->
<my-counter count:from="3"></my-counter>

<!-- Starts counting at startCount -->
<my-counter count:from="this.startCount"></my-counter>

<!-- Update parentCount with the value of count -->
<my-counter count:to="this.parentCount"></my-counter>

<!-- Cross bind parentCount with count -->
<my-counter count:bind="this.parentCount"></my-counter>

<!-- Adds the custom element to the page -->
<my-app></my-app>

<script type="module">
import { StacheElement } from "can";

class MyCounter extends StacheElement {
    static view = `
        Count: <span>{{ this.count }}</span>
        <button on:click='this.increment()'>+1</button>
    `;
    static props = {
        count: { default: 0 },
        increment() {
            this.count++;
        }
    };
}
customElements.define("my-counter", MyCounter);

class MyApp extends StacheElement {
    static view = `
        <p>Calls <code>sayHi</code> when <code>count</code> changes.
            <my-counter on:count="this.sayHi(scope.element.count)"></my-counter>
        </p>
        <p>Start counting at 3.
            <my-counter count:from="3"></my-counter>
        </p>
        <p>Start counting at <code>startCount</code> ({{ this.startCount }}).
            <my-counter count:from="this.startCount"></my-counter>
        </p>
        <p>Update <code>parentCount</code> ({{ this.parentCount }}) with the value of count.
            <my-counter count:to="this.parentCount"></my-counter>
        </p>
        <p>Update <code>bindCount</code> ({{this.bindCount}}) with the value of count.
            <my-counter count:bind="this.bindCount"></my-counter>
        </p>
    `;

    static props = {
        sayHi(count) {
            console.log("MyApp says hi with", count);
        },
        startCount: { default: 4 },
        parentCount: {},
        bindCount: { default: 10 }
    };
}
customElements.define("my-app", MyApp);

</script>

You can also pass data to custom elements directly in html using fromAttribute:

<!-- pass count directly to the <my-counter> element -->
<my-counter count="5"></my-counter>

<!-- pass count directly to the <my-counter> element -->
<my-counter count="5"></my-counter>

<script type="module">
import { StacheElement, type, fromAttribute } from "can";

class MyCounter extends StacheElement {
    static view = `
        Count: <span>{{ this.count }}</span>
        <button on:click='this.increment()'>+1</button>
    `;
    static props = {
        count: { type: type.convert(String), default: 0, bind: fromAttribute },
        increment() {
            this.count++;
        }
    };
}
customElements.define("my-counter", MyCounter);

</script>

Pass can-stache renderers to custom elements to customize layout:

{{< incrementButton }}
    <button on:click="this.add(5)">ADD 5!</button>
{{/ incrementButton }}

{{< countDisplay }}
    You have counted to {{ this.count }}!
{{/ countDisplay }}

<my-counter count:from="5" incrementButton:from="incrementButton" countDisplay:from="countDisplay"></my-counter>

Use call expressions to call the passed renderer or the default renderers if one was not provided.

import { StacheElement } from "can";

class MyCounter extends StacheElement {
    static view = `
        {{ incrementButton(this) }}
        {{ countDisplay(this) }}
    `;
    static props = {
        incrementButton() {
            return `<button on:click="add(1)">+1</button>`;
        },
        countDisplay() {
            return `{{ this.count }}`;
        },
        count: 0,
        add(increment) {
            this.count += increment;
        }
    };
}
customElement.define("my-counter", MyCounter);

<!-- Adds the custom element to the page -->
<my-app></my-app>

<script type="module">
import { StacheElement } from "can";

class MyCounter extends StacheElement {
    static view = `
        {{ incrementButton(this) }}
        {{ countDisplay(this) }}
    `;
    static props = {
        incrementButton() {
            return `<button on:click="add(1)">+1</button>`;
        },
        countDisplay() {
            return `{{ this.count }}`;
        },
        count: 0,
        add(increment) {
            this.count += increment;
        }
    };
}
customElements.define("my-counter", MyCounter);

class MyApp extends StacheElement {
    static view = `
        {{< incrementButton }}
            <button on:click="this.add(5)">ADD 5!</button>
        {{/ incrementButton }}

        {{< countDisplay }}
            You have counted to {{ this.count }}!
        {{/ countDisplay }}

        <my-counter count:from="5" incrementButton:from="incrementButton" countDisplay:from="countDisplay"></my-counter>
    `;
}
customElements.define("my-app", MyApp);
</script>

Data Modeling

Connect data types to a restful service with can-rest-model:

import { restModel } from "can";
import Todo from "//canjs.com/demos/api/todo.mjs";
import TodoList from "//canjs.com/demos/api/todo-list.mjs";

const todoConnection = restModel({
    ObjectType: Todo,
    ArrayType: TodoList,
    url: "/api/todos/{id}"
});

Retrieve, create, update and destroy data programmatically:

Todo.getList({
  // Selects only the todos that match
  filter: {
    complete: { $in: [false, null] }
  },
  // Sort the results of the selection
  sort: "-name",
  // Paginate the sorted result
  page: { start: 0, end: 19 }
}) //-> Promise<TodoList[]>

GET /api/todos?
  filter[complete][$in][]=false&
  filter[complete][$in][]=null&
  sort=-name&
  page[start]=0&
  page[end]=19

{
  "data": [
    {
      "id": 20,
      "name": "mow lawn",
      "complete": false
    },
    // ...
  ]
}

Todo.get({
  id: 5
}) //-> Promise<Todo>

GET /api/todos/5

{
  "id": 5,
  "name": "do dishes",
  "complete": true
}

const todo = new Todo({
  name: "make a model"
})
todo.save()  //-> Promise<Todo>

POST /api/todos
    {
      "name": "make a model",
      "complete": false
    }

{
  "id": 22,
  "name": "make a model",
  "complete": false
}

todo.complete = true;
todo.save()  //-> Promise<Todo>

PUT /api/todos/22
    {
      "name": "make a model",
      "complete": true
    }

{
  "id": 22,
  "name": "make a model",
  "complete": true
}

todo.destroy()  //-> Promise<Todo>

DELETE /api/todos/22

Successful status code (2xx).
Response body is not necessary.

Check the status of request:

const todo = new Todo({ name: "make a model"});

// Return if the todo hasn't been persisted
todo.isNew()    //-> true

// Listen to when any todo is created:
Todo.on("created", (ev, todo) => {});

let savedPromise = todo.save();

// Return if the todo is being created or updated
todo.isSaving() //-> true

savedPromise.then(() => {
    todo.isNew() //-> false
    todo.isSaving() //-> false

    let destroyedPromise = todo.destroy();

    // Return if the todo is being destroyed
    todo.isDestroying() //-> true

    destroyedPromise.then(() => {
        todo.isDestroying() //-> false
    })
});

Connect data types to a restful service and have CanJS automatically manage adding and removing items from lists with can-realtime-rest-model:

import { realtimeRestModel } from "can";

// Define a real time restful model
const todoConnection = realtimeRestModel({
    ObjectType: Todo,
    ArrayType: Todo.List,
    url: "/api/todos/{id}"
});

// Update instances and lists from server-side events:
var loc = window.location;
const socket = new WebSocket('ws://'+loc.host+loc.pathname+"/ws");

socket.addEventListener("todo-created",(event) => {
    todoConnection.createInstance( JSON.parse(event.data) );
});

socket.addEventListener("todo-updated",(event) => {
    todoConnection.updateInstance( JSON.parse(event.data) );
});

socket.addEventListener("todo-removed",(event) => {
    todoConnection.destroyInstance( JSON.parse(event.data) );
});

Simulate a service layer where you can create, retrieve, update and delete (CRUD) records:

import { fixture } from "can";

let todosStore = fixture.store([
    { id: 0, name: "use fixtures", complete: false }
], Todo);

fixture("/api/todos/{id}", todosStore);

Routing

Define routing rules and initialize routing with can-route:

import { route } from "can";

// Create two-way routing rule:
route.register("{page}", { page: "home" });

// Define routing data type
class RouteData extends ObservableObject {
    static props = {
        page: String
    };
}

// Connect routing system to an instance
// of the routing data type
route.data = new RouteData();
// begin routing
route.start();


// Provide access to the route data to your application component
class MyApp extends StacheElement {
    static view = '<page-picker page:from="this.routeData.page"/>';

    static props = {
        routeData: {
            get default() {
                return route.data;
            }
        }
    };
}

Create responsive links in can-stache views with can-stache-route-helpers:

<a href="{{ routeUrl(page='todos') }}"
   class="{{# routeCurrent(page='todos') }}
            inactive
          {{ else }}
            active
          {{/ routeCurrent }}">Todos
</a>

Utilities

Make AJAX requests with can-ajax:

import { ajax } from "can-ajax";

ajax({
    url: "http://query.yahooapis.com/v1/public/yql",
    data: {
        format: "json",
        q: 'select * from geo.places where text="sunnyvale, ca"'
    }
}) //-> Promise<Object>

Perform differences with can-diff:

diff.list(["a","b"], ["a","c"])
//-> [{ type: "splice", index: 1, deleteCount: 1, insert: ["c"] }]

diff.map({ a: "a" },{ a: "A" })
//-> [{ type: "set", key: "a", value: "A" }]

Read and store the results of feature detection with can-globals:

import { globals } from "can";

globals.getKeyValue("isNode")          //-> false
globals.getKeyValue("isBrowserWindow") //-> true
globals.getKeyValue("MutationObserver") //-> MutationObserver

Read and write nested values with can-key:

import { key } from "can";

const task = {
    name: "learn can-key",
    owner: { name: { first: "Justin", last: "Meyer" } }
}

key.delete(task, "owner.name.first");
key.get(task, "owner.name.last") //-> "Meyer"
key.set(task, "owner.name.first", "Bohdi");

Parse a URI into its parts with can-parse-uri:

import { parseURI } from "can";

parseURI("http://foo:8080/bar.html?query#change")
//-> {
//  authority: "//foo:8080",
//  hash: "#change",
//  host: "foo:8080",
//  hostname: "foo",
//  href: "http://foo:8080/bar.html?query#change",
//  pathname: "/bar.html",
//  port: "8080",
//  protocol: "http:",
//  search: "?query"
// }

Convert a string into another primitive type with can-string-to-any:

import { stringToAny } from "can";
stringToAny( "NaN" ); // -> NaN
stringToAny( "44.4" ); // -> 44.4
stringToAny( "false" ); // -> false

Convert one string format to another string format with can-string:

import { string } from "can";

string.camelize("foo-bar")) //-> "fooBar"
string.capitalize("foo")    //-> "Foo"
string.esc("<div>foo</div>")//-> "&lt;div&gt;foo&lt;/div&gt;"
string.hyphenate("fooBar")  //-> "foo-bar"
string.underscore("fooBar") //-> "foo_bar"

Operate on any data type with can-reflect:

import { Reflect } from "can";

// Test the type:
Reflect.isBuiltIn(new Date()) //-> true
Reflect.isBuiltIn(new Todo()) //-> false
Reflect.isConstructorLike(function(){}) //-> false
Reflect.isConstructorLike(Date)         //-> true
Reflect.isListLike([]) //-> true
Reflect.isListLike({}) //-> false
Reflect.isMapLike([]) //-> true
Reflect.isMapLike({}) //-> true
Reflect.isMoreListLikeThanMapLike([]) //-> true
Reflect.isMoreListLikeThanMapLike({}) //-> false
Reflect.isObservableLike(new Todo()) //-> true
Reflect.isObservableLike({})         //-> false
Reflect.isPlainObject({})         //-> true
Reflect.isPlainObject(new Todo()) //-> false
Reflect.isPromiseLike(Promise.resolve()) //-> true
Reflect.isPromiseLike({})                //-> false
Reflect.isValueLike(22) //-> true
Reflect.isValueLike({}) //-> false

// Read and mutate key-value data
const obj = {};
Reflect.setKeyValue(obj,"prop","VALUE");
Reflect.getKeyValue(obj,"prop") //-> "VALUE"
Reflect.deleteKeyValue(obj,"prop","VALUE");

Reflect.assign(obj, { name: "Payal" });

Create types that work with convert using can-type:

import { Reflect, type } from "can";

const MaybeNumber = type.maybe(Number);

Reflect.convert(42, MaybeNumber); // -> 42
Reflect.convert(null, MaybeNumber); // -> null
Reflect.convert(undefined, MaybeNumber); // -> undefined
Reflect.convert("hello world", MaybeNumber); // throws!

const ConvertString = type.convert(String);

Reflect.convert(42, ConvertString); // -> "42"
Reflect.convert(null, ConvertString); // -> "null"
Reflect.convert(undefined, ConvertString); // -> "undefined"
Reflect.convert("hello world", ConvertString); // -> "hello world"

const MaybeConvertBoolean = type.maybeConvert(Boolean);

Reflect.convert("false", MaybeConvertBoolean); // -> false
Reflect.convert(null, MaybeConvertBoolean); // -> null
Reflect.convert(undefined, MaybeConvertBoolean); // -> undefined
Reflect.convert("hello world", MaybeConvertBoolean); // -> true

const StrictNumber = type.check(Number);

Reflect.convert(42, StrictNumber); // -> 42
Reflect.convert(null, StrictNumber); // throws!
Reflect.convert(undefined, StrictNumber); // throws!
Reflect.convert("hello world", StrictNumber); // throws!