JavaScript:暂停函数并等待全局变量 [英] JavaScript: Pause a function and wait on a global variable

问题描述

有一个全局变量 window.listNodes ，它是一个数组.该变量每3秒刷新一次，并依次填充.

There is a global variable window.listNodes that is an array. This variable is refreshed each 3 seconds and is filled sequentially.

另一个函数 onOpen()由用户触发，需要具有包含3个元素(不少于3个元素)的全局变量 window.listNodes .我要做什么:如果全局变量的 .length 不等于3，则程序等待代码的另一部分填充 window.listNodes ，然后开始再次是功能 onOpen().

Another function onOpen() is triggered by the user and needs to have the global variable window.listNodes containing 3 elements, not less. What I seek to do: if the global variable has not a .length equal to 3 then the program waits that the other part of the code fills window.listNodes and then begin again the function onOpen().

socket.onopen = function onOpen() {
        if (window.listNodes.length === 3) {
            // Do something
        } else {
            // Wait and when window.listNodes.length === 3:
            onOpen(); 
        }
    });
};

有一种简单的方法吗?我尝试使用函数 setTimeOut()和生成器函数以及关键字 yield ，但是失败了.

Is there an easy way to do it? I tried with the function setTimeOut() and with a generator function and the keyword yield but I failed.

感谢您的宝贵帮助:)

Thank you for your precious help :)

推荐答案

这可以使用 setTimeout 和自定义间隔来等待，例如500ms，以执行此操作:

This could use setTimeout and a custom interval to wait, for example, 500ms, to do it:

function onOpen() {
        if (window.listNodes.length === 3) {
            // Do something
        } else {
            // Wait and when window.listNodes.length === 3:
            setTimeout(onOpen, 500);
        }
    });
};

socket.onopen = onOpen;

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