es6陣列新增2
阿新 • • 發佈：2018-12-09
<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>陣列擴充套件運算子</title> </head> <ul id='#oUl'> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> </ul> <body> <script type="text/javascript"> let arr = [1,2,3]; let arr2 = [...arr]; //... console.log(arr); console.log(arr2); let strName = 'jiangfei';//類陣列：只要具備length就比較靠譜 json在後面必須加入length console.log([...strName]); console.log([].slice.call(strName)); console.log(Array.from(strName)); let json = { 0:"apple", 1:"banner", 2:"orange" } let json2 = { 0:"apple", 1:"banner", 2:"orange", length:3 } let json3 = { 0:"apple", 1:"banner", 2:"orange", length:2 } console.log(Array.from(json)); console.log(Array.from(json2)); console.log(Array.from(json3)); console.log([].slice.call(json3)); /*console.log([...json2]);*/ /* * arr.keys()每個元素的索引 arr.entriers()所有元素包括索引 ES6陣列的特性 * */ let oUl = document.querySelectorAll('ul li');//偽陣列 let arr3 = [].slice.call(oUl);//將偽陣列轉換為陣列 es5 [].slice.call(偽陣列) let arr4 = Array.from(oUl);//將偽陣列轉換為陣列 es2015 Array.from(偽陣列)把類陣列(獲取一組元素、arguments...)物件轉換為陣列 let arr5 = [...oUl];//將偽陣列轉換為陣列 es6 [...偽陣列] console.log(oUl); console.log(arr3); console.log(arr4); console.log(arr5); function show(){ console.log(arguments); console.log(arguments[0]); console.log(arguments[1]); console.log(arguments[2]); let arr6 =[...arguments]; console.log(arr6); console.log(Array.from(arguments)); console.log([].slice.call(arguments)); console.log(arguments.length); } show(1,2,3,4,5) //Array.of()將一組值轉成陣列 感覺沒啥用 let strAdd = "'sdgfsagraehdfh','sdgfsagraehdfh'"; let arr7 = Array.of('aaaa','bbbb','cccc'); let arr8 = Array.of(strAdd); console.log(arr7); console.log(arr8); //arr.find(function(val,index,arr){return});查找出第一個符合條件的陣列成員，如果沒有找到，返回undefined; let arr9 = [23,12,101,199]; let res = arr9.find((val,index,arr9)=>{ return val>100; }); console.log(res); let arrVal = arr9.find(function(val,index,arr9){ return val>100; }) console.log(arrVal); //arr9.findIndex((val,index,arr9)=>{return val>100;}) 查找出第一個符合條件的陣列成員，並返回他的位置，如果沒有找到，返回undefined; let arrIndex = arr9.findIndex((val,index,arr9)=>{ return val>100; }) console.log(arrIndex); //arr.fill(填充的東西,開始位置,結束位置) 包括起始位置，不包括結束位置 let arr10 =new Array(10); arr10.fill('預設值',2,5); console.log(arr10) //arr.includes()判斷陣列中是否存在指定的元素 返回值為ture/false console.log(arr.includes(1)); </script> </body> </html>