1. call
Effect: Changes this point to call the function to pass in an argument.
Grammar:

function.call(this, arg1, arg2, ...)

Application: The child constructor inherits the properties of the parent constructor

function Father (surname) {
    this.surname = surname;
}
function Son (surname) {
    // Changes this in the parent constructor to this in the child constructor, and passes a value to this attribute.
    Father.call(this, surname);
}
var xiaoming = new Son('xiao');

2. apply
Effect: Changes this point to call the function to pass in an argument.
Grammar:

function.apply(this, [arg1, arg2, ...])

Application: Call a method in Math

var arr = [1, 2, 3];
Math.max.apply(Math, arr);

3. bind
Effect: Change this point to pass in parameter.
Grammar:

function.bind(this, arg1, arg2, ...)

Application: Change the this pointer in setTimeout

var obj = {
    data: 'first',
    init: function () {
        setTimeout(function(){
            this.data = 'last';
        }.bind(this), 3000)
    }
}
obj.init();