JavaScript中reduce()的5个基本用法示例

arr.reduce(callback(accumulator, currentValue[,index[,array]])[, initialValue])

const numbersArr = [67, 90, 100, 37, 60];

const total = numbersArr.reduce(function(accumulator, currentValue){
 console.log("accumulator is " + accumulator + " current value is " + currentValue);
 return accumulator + currentValue;
}, 0);

console.log("total : "+ total);

const studentResult = [67, 90, 100, 37, 60];

const total = studentResult.reduce((accumulator, currentValue) => accumulator +currentValue, 0);

console.log(total); // 354

const studentResult = [
 { subject: '数学', marks: 78 },
 { subject: '物理', marks: 80 },
 { subject: '化学', marks: 93 }
];

const total = studentResult.reduce((accumulator, currentValue) => accumulator + currentValue.marks, 0);

console.log(total); // 251

const twoDArr = [ [1,2], [3,4], [5,6], [7,8] , [9,10] ];

const oneDArr = twoDArr.reduce((accumulator, currentValue) => accumulator.concat(currentValue));

console.log(oneDArr);
// [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ]

const result = [
 {subject: '物理', marks: 41},
 {subject: '化学', marks: 59},
 {subject: '高等数学', marks: 36},
 {subject: '应用数学', marks: 90},
 {subject: '英语', marks: 64},
];

let initialValue = {
 pass: [],
 fail: []
}

const groupedResult = result.reduce((accumulator, current) => {
 (current.marks >= 50) "htmlcode">

const duplicatedsArr = [1, 5, 6, 5, 7, 1, 6, 8, 9, 7];

const removeDuplicatedArr = duplicatedsArr.reduce((accumulator, currentValue) => {
 if(!accumulator.includes(currentValue)){
 accumulator.push(currentValue);
 }
 return accumulator;
}, []);

console.log(removeDuplicatedArr);
// [ 1, 5, 6, 7, 8, 9 ]


总结
在本文中，我们讨论了数组 reduce() 方法。首先介绍 reduce() 方法，然后，使用一个简单的示例讨论其行为。最后，通过示例讨论了 reduce() 方法最常见的五个用例。如果你是JavaScript的初学者，那么本文将对你有所帮助。