编程篇(009)-js 数组拍平(数组扁平化)的六种方式

var arr = [1, 2, [3, 4, 5, [6, 7, 8], 9], 10, [11, 12]];

function fn(arr) {
    let arr1 = [];
    arr.forEach(val => {
        if (val instanceof Array) {
            arr1 = arr1.concat(fn(val));
        } else {
            arr1.push(val);
        }
    });
    return arr1;
}

function fn(arr) {
    return arr.reduce((prev, cur) => {
        return prev.concat(Array.isArray(cur) ? fn(cur) : cur);
    }, []);
}

arr.flat(Infinity);

function fn(arr) {
    let arr1 = [];
    let bStop = true;
    arr.forEach(val => {
        if (Array.isArray(val)) {
            arr1.push(...val);
            bStop = false;
        } else {
            arr1.push(val);
        }
    });
    if (bStop) {
        return arr1;
    }
    return fn(arr1);
}

let arr1 = arr
    .toString()
    .split(",")
    .map(val => {
        return parseInt(val);
    });
console.log(arr1);

function flatten(arr) {
    while (arr.some(item => Array.isArray(item))) {
        arr = [].concat.apply([], arr);
    }
    return arr;
}