Call:调用函数，允许你一个一个地传递参数

Apply: Apply调用函数并允许您将参数作为数组传递

Bind: Bind返回一个新函数，允许传入this数组和任意数量的参数。

var person1 = {firstName: 'Raju', lastName: 'king'}; var person2 = {firstName: 'chandu', lastName: 'shekar'}; function greet(greeting) { console.log(greeting + ' ' + this.firstName + ' ' + this.lastName); } function greet2(greeting) { console.log( 'Hello ' + this.firstName + ' ' + this.lastName); } greet.call(person1, 'Hello'); // Hello Raju king greet.call(person2, 'Hello'); // Hello chandu shekar greet.apply(person1, ['Hello']); // Hello Raju king greet.apply(person2, ['Hello']); // Hello chandu shekar var greetRaju = greet2.bind(person1); var greetChandu = greet2.bind(person2); greetRaju(); // Hello Raju king greetChandu(); // Hello chandu shekar

我认为它们的相同之处在于:它们都可以改变函数的this值。它们的区别是:绑定函数将返回一个新函数作为结果;call和apply方法将立即执行函数，但apply可以接受数组作为参数，并且它将解析分离的数组。绑定函数也可以是curiling。

这里有一篇很好的文章来说明bind()、apply()和call()之间的区别，总结如下。

bind() allows us to easily set which specific object will be bound to this when a function or method is invoked. // This data variable is a global variable​ var data = [ {name:"Samantha", age:12}, {name:"Alexis", age:14} ] var user = { // local data variable​ data :[ {name:"T. Woods", age:37}, {name:"P. Mickelson", age:43} ], showData:function (event) { var randomNum = ((Math.random () * 2 | 0) + 1) - 1; // random number between 0 and 1​ console.log (this.data[randomNum].name + " " + this.data[randomNum].age); } } // Assign the showData method of the user object to a variable​ var showDataVar = user.showData; showDataVar (); // Samantha 12 (from the global data array, not from the local data array)​ /* This happens because showDataVar () is executed as a global function and use of this inside showDataVar () is bound to the global scope, which is the window object in browsers. */ // Bind the showData method to the user object​ var showDataVar = user.showData.bind (user); // Now the we get the value from the user object because the this keyword is bound to the user object​ showDataVar (); // P. Mickelson 43​ bind() allow us to borrow methods // Here we have a cars object that does not have a method to print its data to the console​ var cars = { data:[ {name:"Honda Accord", age:14}, {name:"Tesla Model S", age:2} ] } // We can borrow the showData () method from the user object we defined in the last example.​ // Here we bind the user.showData method to the cars object we just created.​ cars.showData = user.showData.bind (cars); cars.showData (); // Honda Accord 14​ One problem with this example is that we are adding a new method showData on the cars object and we might not want to do that just to borrow a method because the cars object might already have a property or method name showData. We don’t want to overwrite it accidentally. As we will see in our discussion of Apply and Call below, it is best to borrow a method using either the Apply or Call method. bind() allow us to curry a function Function Currying, also known as partial function application, is the use of a function (that accept one or more arguments) that returns a new function with some of the arguments already set. function greet (gender, age, name) { // if a male, use Mr., else use Ms.​ var salutation = gender === "male" ? "Mr. " : "Ms. "; if (age > 25) { return "Hello, " + salutation + name + "."; }else { return "Hey, " + name + "."; } } We can use bind() to curry this greet function // So we are passing null because we are not using the "this" keyword in our greet function. var greetAnAdultMale = greet.bind (null, "male", 45); greetAnAdultMale ("John Hartlove"); // "Hello, Mr. John Hartlove." var greetAYoungster = greet.bind (null, "", 16); greetAYoungster ("Alex"); // "Hey, Alex."​ greetAYoungster ("Emma Waterloo"); // "Hey, Emma Waterloo." apply() or call() to set this value The apply, call, and bind methods are all used to set the this value when invoking a method, and they do it in slightly different ways to allow use direct control and versatility in our JavaScript code. The apply and call methods are almost identical when setting the this value except that you pass the function parameters to apply () as an array, while you have to list the parameters individually to pass them to the call () method. Here is one example to use call or apply to set this in the callback function. // Define an object with some properties and a method​ // We will later pass the method as a callback function to another function​ var clientData = { id: 094545, fullName: "Not Set", // setUserName is a method on the clientData object​ setUserName: function (firstName, lastName) { // this refers to the fullName property in this object​ this.fullName = firstName + " " + lastName; } }; function getUserInput (firstName, lastName, callback, callbackObj) { // The use of the Apply method below will set the "this" value to callbackObj​ callback.apply (callbackObj, [firstName, lastName]); } // The clientData object will be used by the Apply method to set the "this" value​ getUserInput ("Barack", "Obama", clientData.setUserName, clientData); // the fullName property on the clientData was correctly set​ console.log (clientData.fullName); // Barack Obama Borrow functions with apply or call Borrow Array methods Let’s create an array-like object and borrow some array methods to operate on the our array-like object. // An array-like object: note the non-negative integers used as keys​ var anArrayLikeObj = {0:"Martin", 1:78, 2:67, 3:["Letta", "Marieta", "Pauline"], length:4 }; // Make a quick copy and save the results in a real array: // First parameter sets the "this" value​ var newArray = Array.prototype.slice.call (anArrayLikeObj, 0); console.log (newArray); // ["Martin", 78, 67, Array[3]]​ // Search for "Martin" in the array-like object​ console.log (Array.prototype.indexOf.call (anArrayLikeObj, "Martin") === -1 ? false : true); // true​ Another common case is that convert arguments to array as following // We do not define the function with any parameters, yet we can get all the arguments passed to it​ function doSomething () { var args = Array.prototype.slice.call (arguments); console.log (args); } doSomething ("Water", "Salt", "Glue"); // ["Water", "Salt", "Glue"] Borrow other methods var gameController = { scores :[20, 34, 55, 46, 77], avgScore:null, players :[ {name:"Tommy", playerID:987, age:23}, {name:"Pau", playerID:87, age:33} ] } var appController = { scores :[900, 845, 809, 950], avgScore:null, avg :function () { var sumOfScores = this.scores.reduce (function (prev, cur, index, array) { return prev + cur; }); this.avgScore = sumOfScores / this.scores.length; } } // Note that we are using the apply () method, so the 2nd argument has to be an array​ appController.avg.apply (gameController); console.log (gameController.avgScore); // 46.4​ // appController.avgScore is still null; it was not updated, only gameController.avgScore was updated​ console.log (appController.avgScore); // null​ Use apply() to execute variable-arity function

的数学。Max是变量函数的一个例子，

// We can pass any number of arguments to the Math.max () method​
console.log (Math.max (23, 11, 34, 56)); // 56

但是如果我们有一个数字数组要传递给Math.max呢?我们不能这样做:

var allNumbers = [23, 11, 34, 56];
// We cannot pass an array of numbers to the the Math.max method like this​
console.log (Math.max (allNumbers)); // NaN

这就是apply()方法帮助我们执行可变函数的地方。与上述方法不同，我们必须使用apply()传递数字数组，如下所示:

var allNumbers = [23, 11, 34, 56];
// Using the apply () method, we can pass the array of numbers:
console.log (Math.max.apply (null, allNumbers)); // 56

我之前创建了函数对象、函数调用、call/apply和bind之间的比较:

.bind允许您现在设置this值，同时允许您在将来执行该函数，因为它返回一个新的函数对象。

语法

呼叫(thisArg, arg1, arg2， .) (thisArg专心,argsArray) bind(thisArg[， arg1] [， arg2])

Here

thisArg是对象 argArray是一个数组对象 Arg1, arg2, arg3，…是额外的参数

function printBye(message1, message2){ console.log(message1 + " " + this.name + " "+ message2); } var par01 = { name:"John" }; var msgArray = ["Bye", "Never come again..."]; printBye.call(par01, "Bye", "Never come again..."); //Bye John Never come again... printBye.call(par01, msgArray); //Bye,Never come again... John undefined //so call() doesn't work with array and better with comma seperated parameters //printBye.apply(par01, "Bye", "Never come again...");//Error printBye.apply(par01, msgArray); //Bye John Never come again... var func1 = printBye.bind(par01, "Bye", "Never come again..."); func1();//Bye John Never come again... var func2 = printBye.bind(par01, msgArray); func2();//Bye,Never come again... John undefined //so bind() doesn't work with array and better with comma seperated parameters

Call, Apply和Bind之间的基本区别是:

如果您希望执行上下文出现在图的后面，则将使用Bind。

Ex:

var car = { 
  registrationNumber: "007",
  brand: "Mercedes",

  displayDetails: function(ownerName){
    console.log(ownerName + ' this is your car ' + '' + this.registrationNumber + " " + this.brand);
  }
}
car.displayDetails('Nishant'); // **Nishant this is your car 007 Mercedes**

假设我想在其他变量上使用这个方法

var car1 = car.displayDetails('Nishant');
car1(); // undefined

在你应该使用的其他变量中使用car的引用

var car1 = car.displayDetails.bind(car, 'Nishant');
car1(); // Nishant this is your car 007 Mercedes

让我们讨论bind函数的更广泛使用

var func = function() {
 console.log(this)
}.bind(1);

func();
// Number: 1

为什么?因为现在func与编号1绑定，如果我们不使用bind，它将指向全局对象。

var func = function() {
 console.log(this)
}.bind({});

func();
// Object

当您希望同时执行语句时，将使用Call、Apply。

var Name = { 
    work: "SSE",
    age: "25"
}

function displayDetails(ownerName) {
    console.log(ownerName + ", this is your name: " + 'age' + this.age + " " + 'work' + this.work);
}
displayDetails.call(Name, 'Nishant')
// Nishant, this is your name: age25 workSSE

// In apply we pass an array of arguments
displayDetails.apply(Name, ['Nishant'])
// Nishant, this is your name: age25 workSSE