Detailed explanation of JavaScript callback function (callback)

This time I will bring you a detailed explanation of javscript's callback function(callback), what are the precautions when using javscript callback function (callback), the following is a practical case, let's take a look take a look.

Study the callback function. The English name of the callback function is: callback

Function is also an object. Take a look at the written description:

1. The function uses Function()ConstructorFunction object created.
2. The Function object contains a string , and the string contains the javascript code of the function

Look at a demo1:

  var fun = function (x) {     console.log(x)
   };
   fun(100);   //运行结果：100

The above code As you can know, the function can be an object, and parameters can be passed in the function (such as x in demo1). On the contrary, the parameters in the function can also be passed to a function

demo2:

   function get(x, cb) {        var a = 100;
        a = a + x;
        cb(a)
    }
    get(100, function (a) {        console.log(a)
    });    //运行结果：200

As you can see in demo2, there are two parameters in the function get(), one is x and the other is cb, Among them, cb is a function. You can do something in the function cb()

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the PHP Chinese website!

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