javascript - 如何使用javascript为数组中的每个项目设置唯一变量？

Question

我想为每个数字设置一个时间戳，然后根据其自身测试每个数字时间戳。

        var timestamp;
        nums=["1", "2", "3"];
        nums2=nums.map(myFunction);


        function myFunction(num) {

          setInterval(function() {

            var current_time = Math.floor(Date.now() / 1000);

            if (typeof timestamp !== "undefined" ) {
                if (current_time > (timestamp + 60)) {
                    timestamp = Math.floor(Date.now() / 1000);
                    console.log('time stamp reset');
                } else {
                    console.log('time stamp too young will reset after 60 sec');
                }
            } else {
                timestamp = Math.floor(Date.now() / 1000);
                console.log('time stamp set');
            }

         }, 10000);

        }

****如果我运行脚本 20 秒:****

当前输出:

time stamp set

time stamp too young will reset after 60 sec

time stamp too young will reset after 60 sec

*(10 seconds later)*

time stamp too young will reset after 60 sec

time stamp too young will reset after 60 sec

time stamp too young will reset after 60 sec

所需输出:

time stamp set

time stamp set

time stamp set

*(10 seconds later)*

time stamp too young will reset after 60 sec

time stamp too young will reset after 60 sec

time stamp too young will reset after 60 sec

Answer 1

我不明白你在这里想做什么，所以我的答案纯粹基于你的当前输出和所需输出。

您的 timestamp 变量是在 global 范围内声明的，因此第一次调用 myFunction 时，它的值为 undefined，但在后续调用中它将保留一些值，从而产生“当前输出”。

要修复此问题，请将 timestamp 变量移至 myFunction 内。

nums=["1", "2", "3"];
nums2=nums.map(myFunction);


function myFunction(num) {
  var timestamp;

  setInterval(function() {

    var current_time = Math.floor(Date.now() / 1000);

    if (typeof timestamp !== "undefined" ) {
        if (current_time > (timestamp + 60)) {
            timestamp = Math.floor(Date.now() / 1000);
            console.log('time stamp reset');
        } else {
            console.log('time stamp too young will reset after 60 sec');
        }
    } else {
        timestamp = Math.floor(Date.now() / 1000);
        console.log('time stamp set');
    }

 }, 10000);

}