JavaScript数组实现扁平化四种方法详解

var arr = [1, [2, [3, 4, 5]]];
console.log(flatten(arr)); // [1, 2, 3, 4，5]

var a = [1, [2, [3, 4, 5]]];
function flatten(arr) {
    let newArray = []
    for (let i of arr) {
        if (i.constructor === Array) {
            newArray = newArray.concat(flatten(i))
        } else {
            newArray.push(i)
        }
    }
    return newArray
}
console.log(flatten(a)); // [1, 2, 3, 4，5]

var a = [1, [2, [3, 4, 5]]];
function flatten(arr) {
    return arr.reduce((pre,next) => {
        return pre.concat(next instanceof Array ? flatten(next) : next)
    },[])
}
console.log(flatten(a)); //[ 1, 2, 3, 4, 5 ]

// 方法3
var arr = [1, [2, [3, 4]]];
function flatten(arr) {
    while (arr.some(item => Array.isArray(item))) {
        arr = [].concat(...arr);
    }
    return arr;
}
console.log(flatten(arr)); //  [1, 2, 3, 4，5]

// 方法4
var arr = [1, [2, [3, 4]]];
function flatten(arr) {
    return arr.toString().split(',');
}
console.log(flatten(arr)); //  [1, 2, 3, 4]