为什么返回-1在javascript中排序第二个数组之前的第二个值

Question

   function compare (value1, value2) {
    if(value1 < value2) {
        return -1;
    } else if (value1 > value2) {
        return 1;
    } else {
        return 0;
    }
}

var values = [0, 6, 8, 5];
values.sort(compare);
alert(values); // 0,5,6,8

I know that -1 means the first goes before the second and 1 means it goes after but what is the logic behind this? does this -1 0 and 1 apply to methods other than sort?

Answer 1

The way I like to think about it is if you subtract two numbers a from b and you get a negative number that must mean that b was larger, if you get a positive number then a was larger, and if you get 0 then they were both equal. sort() will sort based on which is smaller, larger, and equal.

Ex:

case of -1

a = 6 and b = 7
a - b = -1 // b is larger

case of 1

a = 6 and b = 5
a - b = 1 // a is larger 

case of 0

a = 6 and b = 6 
a - b = 0 // both are equal

Answer 2

 function compare (value1, value2) { return value1 - value2; } var values = [0, 6, 8, 5]; values.sort(compare); console.log(values); // 0,5,6,8