javascript中遍歷數(shù)組有哪幾種方法

javascript中遍歷數(shù)組有哪幾種方法？相信很多沒有經(jīng)驗的人對此束手無策，為此本文總結(jié)了問題出現(xiàn)的原因和解決方法，通過這篇文章希望你能解決這個問題。

有幾種方法可以遍歷數(shù)組，下面將逐個羅列！

while循環(huán)

let index = 0;
const array = [1, 2, 3, 4, 5];

while (index < array.length) {
    console.log(array[index]);
    index++;
}

for循環(huán)

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(gòu)造很有用，但是不會返回新數(shù)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(yīng)用一個函數(shù)然后返回新數(shù)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(shù)組中的每個元素(從左到右)應(yīng)用一個函數(shù)，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(jù)布爾函數(shù)過濾篩選數(shù)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(shù)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(shù)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(jié)束啦，如果還有其他的歡迎補充！

看完上述內(nèi)容，你們掌握javascript中遍歷數(shù)組有哪幾種方法的方法了嗎？如果還想學到更多技能或想了解更多相關(guān)內(nèi)容，歡迎關(guān)注億速云行業(yè)資訊頻道，感謝各位的閱讀！