For example we have a 'forEach' method which can loop though a linked list: forEach(fn) { let node = this.head; let counter = ; while (node) { fn(node, counter); node = node.next; counter++; } } Test: test('applies a transform to each node', () => {…
Most JavaScript developers are familiar with the for loop. One of the most common uses of the for loop is to iterate through the items in an array. In this lesson, we will learn how to replace the for loop with the Array's forEach method - and shorte…
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Sometimes, you might want to convert a JavaScript function that accepts a callback to one that returns a Promiseobject. This lesson shows how to manually wrap a promise-based API around the fs.readFile() function. It also explains how to use the util…
Advantage Avoid re-created instance method to this inside of the constructor. method() implementation The method() takes two parameters: • The name of the new method • The implementation of the method if (typeof Function.prototype.method !== "functio…
From: https://bytenota.com/javascript-convert-image-to-base64-string/ his post shows you two approaches how to convert an image to a Base64 string using JavaScript: HTML5 Canvas and FileReader. 1. Approach 1: HTML5 Canvas example.js function toDataUR…
原文:  http://www.webhek.com/javascript-foreach-call document.querySelectorAll() 返回的并不是我们想当然的数组,而是 NodeList ,对 NodeList ,它里面没有 .forEach 方法,我们使用了这样的方法进行循环: var divs = document.querySelectorAll('div'); [].forEach.call(divs, function(div) { // do whatever…
语法:array.forEach(callbackfn[, thisArg]) 参数说明: array1   必需. 一个数组对象. callbackfn   必需. 一个接受最多三个参数的函数. 对于数组中的每个元素,forEach 都会调用 callbackfn 函数一次. thisArg   可选. 可在 callbackfn 函数中为其引用 this 关键字的对象. 如果省略 thisArg,则 undefined 将用作 this 值 对于数组中的每个元素,forEach 方法都会调用…
One very common operation in programming is to iterate through an Array's contents, apply a test function to each item, and create a new array containing only those items the passed the test. For example, let's say you wanted to loop through an array…
One very common operation in programming is to iterate through an Array's contents, apply a function to each item, and create a new array containing the results. For example, let's say you wanted to loop through an array of stock objects and select o…