自定义列表的两级“for”循环

使用单记号会阻止shell标记提供给 for 循环:

#!/bin/sh

for i in -1 4.5
do  for j in 0 -2.2
    do  # -- keeps the highly portable printf utility from 
        # interpreting '-' as an argument 
        printf -- "$i" "$j\n" 
    done
done

var a = [1,2,3];
var b = [1,2,3];

for (i in a) {
    for (j in b) {
        alert (i + j);
    }
}

我还创建了一个jsfiddle: http://jsfiddle.net/f8k5tpqm/1/