Use of JavaScript apply, call, and bind methods __java

First, these three methods are the scopes that extend the function by changing the point of the This object of the function. Each function contains three methods that are not inherited. They are used in the same ways to invoke a function in a specific scope. The first argument is the object to point to. Can be passed parameters, the way to pass the parameter is different. Apply, call return function run result, bind generates a function to pass the parameter: apply (obj, [parameter 1, Parameter 2, ...]), call (obj, parameter 1, parameter 2, ...), bind at the generated function execution place to pass the parameter.

> name = ' li Ming ' '
li Ming '
> Age = ' > Let
people = {name: ' Little Red ', age:17}
undefined
> Func tion SayHello () {
... console.log ("hello!" + this.name);
... }
Undefined
> SayHello ()
hello! liming
undefined
> sayhello.apply (People)//This points to the People object
hello!        //Direct return to run results
undefined
> Sayhello.call (People);//This points to people object
hello! Little Red        //Direct return to run results
undefined
> Sayhello.bind (SayHello)  //Return a new function
[Function:bound SayHello]
> Sayhello.bind (People) ()  //Can be used in (parameters) to
hello! small red
undefined
> Newsayhello = Sayhello.bind (People)
[function:bound SayHello]
> Newsayhello ()
hello! Xiao Hong

Later found a section of Function.prototype.apply.call (FN, obj, args) code, what ghost ...

After reading the This object that knows to bind a function, you can write this: fn.apply (obj, args), but if the function customizes the Apply method, the This object to bind a function can only be written as Function.prototype.apply.call (FN, obj, args). Simplified method Use (ES6): reflect.apply