ATG Precision technology-front face test

1. Please write down the following results

 for (var i=0; i<10; i++) {    setTimeout (function () {        console.log (i)    },ten)}

Results: printed 10 times 190
Analytical:
The study is the scope and asynchronous knowledge points, which is unique to JS knowledge points, other programming languages are not
A: Encountered asynchronous code, the program does not wait, and the code continues to execute, that is, the For loop executes first, and then come back to execute the callback in SetTime, when I has been accumulated to 10
B: Because the JS language does not have block-level scope, so I inside the timer is the value of the external I, so the internal printing of the timer I, is already 10

ATG Precision technology-front face test