将从诺言返回的值分配给全局变量 [英] Assign a value returned from a promise to a global variable

问题描述

我正在尝试从量角器读取浏览器的内存值，并将其存储在全局对象中.为此，我要获取window.performance.memory对象，然后解决对每个内存值进行检查的承诺.

I'm trying to read the browser memory values from Protractor and store them in a global object. To do that I'm getting the window.performance.memory object and then resolving the promise to inspect each of the memory values.

问题是我似乎无法将值分配给全局变量.我已经尝试了以下代码，但似乎效果不佳:

The problem is that I cannot seem to be able to assign the value to a global variable. I've tried the following code, which doesn't seem to work quite well:

 this.measureMemory = function () {

    var HeapSizeLimit;

    browser.driver.executeScript(function () {
        return window.performance.memory;
    }).then(function (memoryValues) {
        HeapSizeLimit = memoryValues.jsHeapSizeLimit;
        console.log('Variable within the promise: ' + HeapSizeLimit);
    });
    console.log('Variable outside the promise: ' + HeapSizeLimit);
};

这将返回:

   Variable outside the promise: undefined
   Variable within the promise: 750780416

推荐答案

因为 console.log('Variable outside the promise: ' + HeapSizeLimit); 在HeapSizeLimit = memoryValues.jsHeapSizeLimit;之前执行.如果在约定之后就行了，那并不意味着执行顺序是相同的.

Because console.log('Variable outside the promise: ' + HeapSizeLimit); is executed before HeapSizeLimit = memoryValues.jsHeapSizeLimit;. If it's on the line after the promise, doesn't mean the execute order is the same.

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