这是因为闭包捕获的是变量 i 本身，而不是当前值.试试:

It's because the closure captures the variable i itself, not the current value. Try:

for (var i = 0; i < a.length; i++) (function(i)
{
    calcRoute(fixedLocation, my_cities[i].address, function(response) {

        // i want here to have the current "i" here

    });             

}) (i);

这将为每次循环迭代创建一个新的 i 变量.

which will create a new i variable for each loop iteration.