Javascript代码进入无限循环

Question

the following code goes into infinite loop and a crash in the webpage I need to know what's wrong with it?

    for (var i = 0; i < 2; i+1) {
            for (var j = i; j < 8; j + 2) {
                console.log(arr[j].Qu);
            }
            console.log(arr[i]);
        }

Answer 1

i+1 doesn't update i's value, therefor, the i always has value 1, as it takes 0+1 in every run, thus never being > 2 and never ending You need to change it with i++, like this

for (var i = 0; i < 2; i++) {

Also, as @Xufox points out, udpate your J loop with

for (var j = i; j < 8; j += 2) {

i+1 is not an assign operation, that's why you need to assign the value urself. i++ and j+=2 translate to

i = i+1;
j= j+2;

and the result of the righthand operation is self-assigned to the variable

Answer 2

Value is not assigned back to variable.

 for (var i = 0; i < 2; i+=1) { // i++
            for (var j = i; j < 8; j+=2) {
                console.log(arr[j].Qu);
            }
            console.log(arr[i]);
        }

Answer 3

i+1 doesn't modify i value. You could write instead i++ .

Similarly, j + 2 doesn't update j. You should write j += 2 .

Here is the corrected code :

for (var i = 0; i < 2; i++) {
    for (var j = i; j < 8; j += 2) {
        console.log(arr[j].Qu);
    }
    console.log(arr[i]);
}

Answer 4

 for (var i = 0; i < 2; i+=1) { for (var j = i; j < 8; j+= 2) { console.log(arr[j]); } console.log(arr[i]); }