JavaScript closure issues in a detailed

Before you see a piece of code, it is not understandable, and then find the information and find the network Daniel consulted, finally understand the code, and then take out a summary.

1. Digging pits

Take a look at the code first:

varArrtest = []; for(vari =0; I <3; i++) {//Note that the function does not pass arguments into the function body Arrtest.push (function() {Console. log (' >>> '+ i); })}//arrtest=[function(){Console. log (' >>> '+i)},function(){Console. log (' >>> '+i)},function(){Console. log (' >>> '+i)}]Console. log (arrtest[0].tostring ());//function(){Console. log (' >>> ', +i)}Console. log (i);Console. log ('-------------');//Length can be replaced with l simple words, reduce code length for(vari =0, arrlength = Arrtest.length; i < arrlength; i++) {Console. log (i); Arrtest[i] ();}//The value of the validated IConsole. log (the value of ' I ' is '+ i);//i=3Console. log (' End for '); for(varj =0, arrlength = Arrtest.length; J < Arrlength; J + +) {Console. log (j); ARRTEST[J] ();} Arrtest = [function() {Console. log (' >>> '+ i)},function() {Console. log (' >>> '+ i)},function() {Console. log (' >>> '+ i)}]

The result is like this:

How does that happen when you traverse the entire function and print out the results we want to 0,1,2?

/*对函数进行改造，当执行循环的时候，打印0，1，2 */var arrTest1 = [];for (var03; i++) {    //构造一个立即执行的函数将函数的返回结果添加入数组中    (function(n) {        arrTest1.push(function() {            console.log(‘>>>‘ + n);        });    })(i);}console.log(arrTest1);for (var0, l = arrTest1.length; i < l; i++) {    arrTest1[i]();}

Printing results:

JavaScript closure issues in a detailed