JavaScript design pattern and open practice Learning (a) Function.prototype.bind

Use Function.prototype.bind to wrap the Func function

1, simplified version of BIND

function.prototype.bind=function  (context) {        var self=this//  Save the original function        return functions ()            {return  self.apply (context, arguments);        }    };     var obj={name: ' Seven '};     var func=function() {        alert (this. Name);    }. Bind (obj);    Func ();

2. Bind with Parameters

 function.prototype.bind=function   () {
    var  self=; Context  =[].shift.call (arguments); //  The this context that needs to be bound  args=[].slice.call (arguments); //         remaining arguments  return  function   () {  Self.apply (Context,[].concat.call (Args,[].slice.call (arguments)); 
//equal to  return self.apply (context,args.concat (arguments)); parameters passed in after this arguments 

var obj={name: ' Seven 'var func=function(a,b,c,d) {alert ( This . name); // output seven alert ([a,b,c,d]); // output [1,2,3,4] }. Bind (obj,1,2) func (3,4);

Note:

1) Arguments object: The arguments object is not an array and accesses a single parameter in the same way as an array element.

2) Shift usage: Used to remove the first element of the array and return the value of the first element.

2) Slice usage: the slice () method returns the selected element from an existing array.

3) concat usage: the concat () method is used to connect two or more arrays.

JavaScript design pattern and open practice Learning (a) Function.prototype.bind