總結javascript中遍歷數組的幾種方法

本篇文章給大家總結了一些javascript遍歷數組的幾種方法。有一定的參考價值，有需要的朋友可以參考一下，希望對大家有所幫助。

有幾種方法可以遍歷數組，下面將逐個羅列！

while循環

let index = 0; const array = [1, 2, 3, 4, 5];  while (index < array.length) {     console.log(array[index]);     index++; }

for循環

const array = [1,2,3,4,5]; for(let index=0;index<array.length;index++){     console.log(array[index]); } for(let index in array){     console.log(array[index]); }

forEach

const array=[1,2,3,4,5]; array.forEach(function(current_value,index,array){     console.log(`At index ${index} in array ${array} the value is ${current_value}`) })

map

最后一個構造很有用，但是不會返回新數組，這對于你的特定情況可能是不希望的。map通過對每個元素應用一個函數然后返回新數組來解決此問題。

const array = [1,2,3,4,5]; const square = x =>Math.pow(x,2); const squares = array.map(square); console.log(`${array}`); console.log(`${squares}`)

reduce

reduce()方法對累加器和數組中的每個元素(從左到右)應用一個函數，以將其減小為單個值

const array = [1,2,3,4,5]; const sum = (x,y) => x + y;  const array_sum = array.reduce(sum,0); console.log(`the sum of arrray:${array} is ${array_sum}`);

filter

根據布爾函數過濾篩選數組中的元素

const array = [1,2,3,4,5]; const even = x => x%2 === 0; const even_array = array.filter(even); console.log(`even numbers in array ${array} : ${even_array}`);

every

得到了一個數組，想測試每個元素是否滿足給定條件

const array = [1,2,3,4,5,8]; const under_six = x => x<6; if(array.every(under_six)){     console.log(`every elemnet in the array is less than 6`); } else{     console.log(`at least one element in the array was bigger than 6`); }

some

測試是否至少有一個元素與布爾函數匹配

const array = [2,4,5,6,8]; const over_five = x => x>5;  if(array.some(over_five)){     console.log(`at least one element bigger than 5 was found`); } else{     console.log(`no element bigger than 5 was found`); }

到此就結束啦，