js 对象数组 去重

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去重 函数unique

function unique(arr, key) {
    if (!arr) return arr
    if (key === undefined) return [...new Set(arr)]
    const map = {
        'string': e => e[key],
        'function': e => key(e),
    }
    const fn = map[typeof key]
    const obj = arr.reduce((o,e) => (o[fn(e)]=e, o), {})
    return Object.values(obj)
}

普通数组去重

unique([1, 1, 1, 14, 1, 4, 4, 1, 13])

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对象数组 去重

const list = [
    { id: 0,    name: '小明',    age: 13 },
    { id: 1,    name: '小明',    age: 99 },
    { id: 2,    name: '小明',    age: 23 },
    { id: 3,    name: '小红',    age: 42 },
    { id: 4,    name: '小明',    age: 13 },
    { id: 5,    name: '小芳',    age: 35 },
    { id: 0,    name: '小明',    age: 13 },
    { id: 7,    name: '',    age: 23 },
    { id: 8,    name: 'lm',    age: 22 },
    { id: 9,    name: 'xh',    age: 79 }
]

unique(list, 'id')    // id 去重
unique(list, 'age') // age 去重
unique(list, 'name')    // name 去重
unique(list, e => e.name + e.age)    // name+age 去重

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实现hashcode 去重

function hashcode(str) {
    str = typeof str === 'object' ? JSON.stringify(str) : str
    var hash = 0, i, chr, len;
    if (str.length === 0) return hash;
    for (i = 0, len = str.length; i < len; i++) {
        chr   = str.charCodeAt(i);
        hash  = ((hash << 5) - hash) + chr;
            hash |= 0; // Convert to 32bit integer
    }
    return hash;
}

unique(list, e => hashcode(e))        // hashcode 去重

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