call apply bind dow we need code example
Example 1: call apply bind
const obj = { number: 1 }
function foo() {
console.log(this.number)
}
//bind - binds obj's 'this' context to foo, but doesn't call it
const newFoo = foo.bind(obj)
//call/apply - binds obj's 'this' context to foo, then calls it
foo.call(obj, /*arg1*/, /*arg2*/)
foo.apply(obj, [/*arg1*/, /*arg2*/])
//Only difference between call/apply is argument passing - ',' vs '[]'
Example 2: what is call, apply, bind
Answer in SIMPLEST form
Call invokes the function and allows you to pass in arguments one by one.
Apply invokes the function and allows you to pass in arguments as an array.
Bind returns a new function, allowing you to pass in a this array and any number of arguments.
Apply vs. Call vs. Bind Examples
--------------
Call
var person1 = {firstName: 'Jon', lastName: 'Kuperman'};
var person2 = {firstName: 'Kelly', lastName: 'King'};
function say(greeting) {
console.log(greeting + ' ' + this.firstName + ' ' + this.lastName);
}
say.call(person1, 'Hello'); // Hello Jon Kuperman
say.call(person2, 'Hello'); // Hello Kelly King
--------------
Apply
var person1 = {firstName: 'Jon', lastName: 'Kuperman'};
var person2 = {firstName: 'Kelly', lastName: 'King'};
function say(greeting) {
console.log(greeting + ' ' + this.firstName + ' ' + this.lastName);
}
say.apply(person1, ['Hello']); // Hello Jon Kuperman
say.apply(person2, ['Hello']); // Hello Kelly King
-------------
Bind
var person1 = {firstName: 'Jon', lastName: 'Kuperman'};
var person2 = {firstName: 'Kelly', lastName: 'King'};
function say() {
console.log('Hello ' + this.firstName + ' ' + this.lastName);
}
var sayHelloJon = say.bind(person1);
var sayHelloKelly = say.bind(person2);
sayHelloJon(); // Hello Jon Kuperman
sayHelloKelly(); // Hello Kelly King