数组去重

# 双层循环

function unique(array) {
    var res = [];
    for (var i = 0, arrayLen = array.length; i < arrayLen; i++) {
        for (var j = 0, resLen = res.length; j < resLen; j++) {
            if (array[i] === res[j]) break;
        }
        if (j === resLen) res.push(array[i]);
    }
    return res;
}

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# indexOf

function unique(array) {
    var res = [];
    for (var i = 0, len = array.length; i < len; i++) {
        var current = array[i];
        if (res.indexOf(current) === -1) res.push(current);
    }
    return res;
}

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# 排序后去重

function unique(array) {
    var res = [];
    var sortedArray = array.concat().sort();
    console.log(sortedArray);
    var seen;
    for (var i = 0, len = sortedArray.length; i < len; i++) {
        if (!i || seen !== sortedArray[i]) res.push(sortedArray[i]);
        seen = sortedArray[i];
    }
    return res;
}

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# filter

function unique(array) {
    return array.concat().sort().filter(function (item, index, array) {
        return !index || item !== array[index - 1];
    });
}

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# ES6

# Set

const unique = (a) => [...new Set(a)];

# Map

const unique = (arr) => {
    const seen = new Map();
    return arr.filter(a => !seen.has(a) && seen.set(a, 1));
};

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#前端 #编程题

上次更新: 2022/09/07, 15:54:26

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