replaceAll()的第二个参数replacement除了为字符串,也可以是一个函数,该函数的返回值将替换掉第一个参数searchValue匹配的文本。 'aabbcc'.replaceAll('b', () => '_') // 'aa__cc' 1. 三、对象方法 1、Object.keys() Object.keys() 方法返回一个所有元素为字符串的数组
JavaScript Array indexOf() TheindexOf()method searches an array for an element value and returns its position. Note:The first item has position 0, the second item has position 1, and so on. Example Search an array for the item "Apple": ...
We are going to demonstrate two functions to search arrays. The first function will return1or0if a value that is passed exists in an array of simple values. If the value exists, the function will return1, and if the value does nto exist in the array, it will return0. Let’s look a...
Finding a value in an array is useful for effective data analysis. Learn how to discover what a JavaScript Array contains using indexOf, includes, for loop, some methods and more.
[].map();基本用法跟forEach方法类似:array.map(callback,[ thisObject]);callback的参数也类似:[].map(function(value, index, array) { // … });map方法的作用不难理解,“映射”嘛,也就是原数组被“映射”成对应新数组。下面这个例子是数值项求平方:var data = [1, 2, 3, 4]; var arrayOf...
propertyIsEnumerable(propertyName):用于判断给定的属性是否可以使用for-in语句枚举 toLocaleString():返回对象的字符串表示,该字符串反映对象所在的本地化执行环境 toString():返回对象的字符串表示 valueOf():返回对象对应的字符串、数值或布尔值表示。通常与toString()的返回值相同。 # 操作符 # 一元操作符 递增/...
array.keys() : 包含原始数组的键名(key), 键名的遍历器对象,可以用 for...of 循环进行遍历。 array.values() : 包含原始数组的键值(value), 键值的遍历器对象,可以用 for...of 循环进行遍历。 array.entries() : 包含原始数组的键名(key)、键值(value),键值对的遍历器对象,可以用 for...of 循环进行...
首先我们先来看一下谷歌浏览器里Array内置的方法有多少,如下↓ 真是不看不知道,一看吓一跳,在我印象里数组的使用方法加上ES6新语法最多也就十几个吧 这里我数了一下从concat到valueOf总共37个(你敢信,无知啊),下面的“__”开头的就暂时不说了
for (let x of values(fruits)) { text += x + "";} Try it Yourself » Example Use the built in Object.values() method: // Create an Array const fruits = ["Banana", "Orange", "Apple", "Mango"]; // List the Values let text = ""; for (let x of Object.values(fruits)...
What labels should be used: should it use the standard built-in labels for the languages ("... minutes ago","... min. ago","...m"), or should it use custom ones, or should it skip using relative time labels in some cases and instead output something like"Dec 11, 2015". ...