[转]数组降维

1.朴素转换

function reduceDimension(arr) {
    var reduced = [];
    for (var i = 0; i < arr.length; i++) {
        for (var j = 0; j < arr[i].length; j++) {
            reduced.push(arr[i][j]);
        }
    }
    return reduced;
}

2.concat数组拼接

function reduceDimension(arr) {
    var reduced = [];
    for (var i = 0; i < arr.length; i++){
        reduced = reduced.concat(arr[i]);
    }
    return reduced;
}

3.apply(thisArg,[argsArray])

function reduceDimension(arr) {
    return Array.prototype.concat.apply([], arr);
}

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