JavaScript Array
Javascript Array forEach()中无法return和break，代替方法some()与every()「建议收藏」
大家好，又见面了，我是你们的朋友全栈君。 我们都知道for循环里要跳出整个循环是使用break，但在数组中用forEach循环如要退出整个循环使用break会报错，使用return也不能跳出循环。使用break将会报错：var arr = [1,2,3,4,5]; var num = 3; arr.forEach(function(v){ if(v == num) { br
日期 2023-06-12 10:48:40
JavaScript Array的map方法
大家好，又见面了，我是你们的朋友全栈君。 定义和用法： map方法返回一个新数组，不会改变原数组 数组中的元素为原始数组元素调用函数处理后的值 array.map(function(currentValue,index,arr), thisValue)复制其中function的三个参数分别是：参数描述currentValue必须。当前元素的值index可选值。当前元素的索引值arr可选值。
日期 2023-06-12 10:48:40【说站】javascript中Array.join()方法如何使用
javascript中Array.join()方法如何使用说明 1、将数组中的所有元素转换为字符串并连接在一起，并返回最终生成的字符串。2、可以指定可选的字符串在生成的文字串中分割数组的元素。如果没有指定分隔符，则默认使用逗号。Arrray.join()方法是String.split()方法的逆向操作，后者将文字串分成几个块组成一个数组。实例var a = [1, 2, 3]; // 创建
日期 2023-06-12 10:48:40
Javascriptarray类数组操作方法
push方法将新元素添加到一个数组中，并返回数组的新长度值。arrayObj.push([item1[item2[...[itemN]]]])参数arrayObj必选项。一个Array对象。item,item2,...itemN可选项。该Array的新元素。说明push方法将以新元素出现的顺序添加这些元素。如果参数之一为数组，那么该数组将作为单个元素添加到数组中。如果要合并两个或多个数组中的元素
日期 2023-06-12 10:48:40javascriptArray数组对象的扩展函数代码
今天重点讲下如何给Array对象扩展1、直接在Array.prototype上扩展2、用自己方法对数组对象进行扩展直接在Array.prototype上扩展,不能直接对dom对象使用(如:document.getElementsByTagName("div")得到的nodeList);对有洁癖的同学而言也破了原始生态环境的:)先来看下yui操作数组的一些方法，这里我对源码简单剥离并改动了下复制代
日期 2023-06-12 10:48:40
在javascript将NodeList作为Array数组处理的方法
比如：复制代码代码如下:varanchors=document.getElementsByTagName("a");for(i=0;i<anchors.length;i++){varele=anchors[i];//取某一个元素//somecodehere}上面的代码表示获取文档中的所有链接元素，然后遍历做一些事情。也许你会问，通过这种方法获取的这一组dom元素不就是一个数组吗？你看，你都
日期 2023-06-12 10:48:40JavaScriptisArray()函数判断对象类型的种种方法
1)typeof运算符typeof是一元运算符，返回结果是一个说明运算数类型的字符串。如："number"，"string"，"boolean"，"object"，"function"，"undefined"（可用于判断变量是否存在）。但typeof的能力有限，其对于Date、RegExp类型返回的都是"object"。如：复制代码代码如下:typeof{};//"object"typeof[]
日期 2023-06-12 10:48:40JavaScript高级程序设计读书笔记之九本地对象Array
创建Array对象复制代码代码如下://onevaraValues=newArray();//twovaraValues=newArray(20);//threevaraColors=newArray();aColors[0]="red";aColors[1]="green";aColors[2]="blue";//fourvaraColors=newArray("red","green","b
日期 2023-06-12 10:48:40
javaScriptarray(数组)使用字符串作为数组下标的方法
Array是从Object那里继承下。它具备Object所有的功能和特性。下面是Object的情况：新建：var object = new Object();增加：object[strIndex] = value;(strIndex为string)删除：delete object[strIndex];遍历：for ( var strObjIndex in object)object[strOb
日期 2023-06-12 10:48:40JavaScriptArray对象扩展indexOf()方法
背景：JavaScript中Array对象的标准方法中，没有indexOf()方法，可通过下面的代码扩展。复制代码代码如下:if(!Array.prototype.indexOf){Array.prototype.indexOf=function(elt){varlen=this.length>>>0;varfrom=Number(arguments[1])||0;from=(
日期 2023-06-12 10:48:40Javascript中Array.prototype.map()详解
在我们日常开发中，操作和转换数组是一件很常见的操作，下面我们来看一个实例： 复制代码代码如下: vardesColors=[], srcColors=[ {r:255,g:255,b:255},//White {r:128,g:128,b:128},//Gray {r:0, g:0, b:0 } //Black ]; for(vari=
日期 2023-06-12 10:48:40JavaScript实现的in_array函数
在JS中要判断一个值是否在数组中并没有函数直接使用，如PHP中就有in_array()这个函数。但我们可以写一个类似in_array()函数来判断是一个值否在函数中。 /** *JS判断一个值是否存在数组中 */ //定义一个判断函数 varin_array=function(arr){ //判断参数是不是数组 varisArr=arr&&console.log( type
日期 2023-06-12 10:48:40JavaScript 数组(Array)对象
Array 对象 Array 对象用于在单个的变量中存储多个值。 创建 Array 对象的语法： new Array(); new Array(size); new Array(element0, element1, ..., elementn); 参数 参数 size 是期望的数组元素个数。返回的数组，length 字段将被设为 size 的值。 参数
日期 2023-06-12 10:48:40[Javascript] Chunk array
Array.from() is a great way to chunk up arrays because of the secondary argument being a map function. const hugeArray = Array.from({length: 76}, (_, i) => i) function chunkify(array, chun
日期 2023-06-12 10:48:40![[Javascript] Swap array item in place using splice()](/scriptcss/images/04.png)
[Javascript] Swap array item in place using splice()
function swap(array, i, j) { const [item] = array.splice(i, 1) // get item and remove this item from array array.splice(j, 0, item) }
日期 2023-06-12 10:48:40[Javascript] Wrap Arrays with Proxy
In contrast to other built-ins, Arrays can be wrapped transparently: const p = new Proxy(new Array(), {}); p.push('a'); assert.equal(p.length, 1); p.length = 0; assert.equal(p.length, 0); The rea
日期 2023-06-12 10:48:40[Javascript] Yield an Array, String, or Any Iterable from a Generator (yield*)
Generators allow you to use the yield * syntax to yield each iteration of nested iterable as part of the main iterations. This enables you to combine multiple arrays, strings, or any iterable with an
日期 2023-06-12 10:48:40[Javascript] Creating an Iterator from an Array
Every Array has a function which you can use to create an iterator. This function can only be accessed by using the Symbol.iterator as a key on the Array. Once you have created your iterato
日期 2023-06-12 10:48:40[ES2019] Use JavaScript ES2019 flatMap to Map and Filter an Array
ES2019 introduces the Array.prototype.flatMap method. In this lesson, we'll investigate a common use case for mapping and filtering an array in a single iteration. We'll then see how to do this using
日期 2023-06-12 10:48:40[Functional Programming] Draw Items from One JavaScript Array to Another using a Pair ADT
We want to be able to pick nine random cards from an array of twelve cards, but can run into problems of keeping both the cards already draw and the cards left to draw from. Tracking two bits of stat
日期 2023-06-12 10:48:40[Javascript] Use a custom sort function on an Array in Javascript
Sorting in Javascript with sort uses lexical sorting by default, which means it will sort in alphabetical order. That's fine for strings of characters, but it means that arrays of
日期 2023-06-12 10:48:40[Javascript] Different ways to create an new array/object based on existing array/object
Array: 1. slice() const newAry = ary.slice() 2. concat const newAry = [].concat(ary) 3. spread opreator: const newAry = [...ary] 4. Array.from: const newAry = Array.from(a
日期 2023-06-12 10:48:40[Javascript] Array methods in depth - some
some returns a boolean value after passing each item in the source array through the test function that you pass in as the first parameter. This makes it well suited to the types of q
日期 2023-06-12 10:48:40[Javascript] Array methods in depth - filter
Array filter creates a new array with all elements that pass the test implemented by the provided function. In this lesson we discuss how only a truthy or falsey value is required as the return value
日期 2023-06-12 10:48:40[Javascript] Array - join()
The join() method joins all elements of an array into a string. var name = 'shane osbourne'; var upper = name.split(' ') // [shane, osbourne] .map(x => x.charAt(0).toUpperCase() + x.slice
日期 2023-06-12 10:48:40[Javascript] The Array filter method
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 exa
日期 2023-06-12 10:48:40[Javascript] Swap array item in place using splice()
function swap(array, i, j) { const [item] = array.splice(i, 1) // get item and remove this item from array array.splice(j, 0, item) }
日期 2023-06-12 10:48:40[Javascript] Create a Custom Iterator for Any Array
Using Symbol.iterator, you can create custom iterators that can be used inside of for loops and Array spreads. This lesson walks you through creating a function to create iterators from arrays that y
日期 2023-06-12 10:48:40[Tips + Javascript] Make a unique array
To make an array uniqued, we can use Set() from Javascript. const ary = ["a", "b", "c", "a", "d", "c"]; console.log(new Set(ary)); We can see that all the duplicated value have been removed,
日期 2023-06-12 10:48:40[Javascript] Array methods in depth - filter
Array filter creates a new array with all elements that pass the test implemented by the provided function. In this lesson we discuss how only a truthy or falsey value is required as the return value
日期 2023-06-12 10:48:40[Javascript] Array - Conact
For example there are two array of object and you want to print out each element, it is bad if you use two forEach method on each array: var people1 = [ { name: 'Mikko' }, { name: 'Rad
日期 2023-06-12 10:48:40