1，常規雙循環去重（缺點：循環次數較多）

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Array.prototype.unique1 = function(){if(this === null){throw new TypeError('"this" is null or not defined');}let that = Object(this),len = that.length >>> 0;let res = [that[0]];for(let i = 1; i < len; i++){let falg = false;for(let j = 0; j < res.length; j++){if(that[i] === res[j]){falg = true;break;}}if(!falg){res.push(this[i]);}}return res;
}

注意：

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（1，必須在第二個循環外push到新的數組

（2，減少循環次數，在第二個循環中找到相等值，馬上退出該循環

（3，每次循環對falg檢驗

（4，由于第一值直接賦值，所以不用檢測第一個值

2，數組的sort先排序再去重（缺點：返回數組為排序后的順序）

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Array.prototype.unique2 = function(){if(this === null){throw new TypeError('"this" is null or not defined');}let that = Object(this).sort(),len = that.length >>> 0,res = [that[0]];for(let i = 1; i < len; i++){if(that[i] !== res[res.length - 1]){res.push(that[i]);}}return res;
}

3，對象鍵值不重復（缺點：占內存）

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Array.prototype.unique3 = function(){if(this === null){throw new TypeError('"this" is null or not defined');}let that = Object(this),len = that.length >>> 0,obj = {},res = [];for(let i = 0; i < len; i++){let type = typeof that[i];if(!obj[that[i]]){res.push(that[i]);obj[that[i]] = [type];}else if(obj[that[i]].indexOf(type) === -1){res.push(that[i]);obj[that[i]].push(type);}}return res;
}

4，indexOf檢測新數組（優點：簡單）

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Array.prototype.unique4 = function(){if(this === null){throw new TypeError('"this" is null or not defined');}let that = Object(this),len = that.length >>> 0,res = [that[0]];for(let i = 1; i < len; i++){if(res.indexOf(that[i]) === -1){res.push(that[i]);}}return res;
}

5，indexOf檢測原數組

Array.prototype.unique5 = function(){if(this === null){throw new TypeError('"this" is null or not defined');}let that = Object(this),len = that.length >>> 0,res = [that[0]];for(let i = 1; i < len; i++){if(that.indexOf(that[i]) === i){res.push(that[i]);}}return res;
}

6，數組的every方法

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Array.prototype.unique6 = function(){if(this === null){throw new TypeError('"this" is null or not defined');}let that = Object(this),len = that.length >>> 0,res = [that[0]];for(let i = 1; i < len; i++){if(res.every(function(val){return val !== that[i]})){res.push(that[i]);}}return res;
}

注意：如果發現了一個這樣的元素，every 方法將會立即返回 false。否則，callback 為每一個元素返回 true，every 就會返回 true。

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7，數組的some方法

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Array.prototype.unique10 = function(){if(this === null){throw new TypeError('"this" is null or not defined');}let that = Object(this),len = that.length >>> 0,res = [that[0]];for(let i = 1; i < len; i++){if(!res.some(function(val){return val === that[i]})){res.push(that[i]);}}return res;
}

注意：如果找到了這樣一個值，some 將會立即返回 true。否則，some 返回 false。
8，數組的includes方法

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Array.prototype.unique7 = function(){if(this === null){throw new TypeError('"this" is null or not defined');}let that = Object(this),len = that.length >>> 0,res = [that[0]];for(let i = 1; i < len; i++){if(!res.includes(that[i])){res.push(that[i]);}}return res;
}

9，數組的filter方法

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Array.prototype.unique8 = function(){if(this === null){throw new TypeError('"this" is null or not defined');}let that = Object(this),len = that.length >>> 0,res = [that[0]];for(let i = 1; i < len; i++){if(res.filter(function(val){return val === that[i]}).length === 0){res.push(that[i]);}}return res;
}

10，數組的find方法（缺點：沒有做0或者false這個一類判斷）

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Array.prototype.unique9 = function(){if(this === null){throw new TypeError('"this" is null or not defined');}let that = Object(this),len = that.length >>> 0,res = [that[0]];for(let i = 1; i < len; i++){if(!res.find(function(val){return val === that[i]})){res.push(that[i]);}}return res;
}

還有lastIndexOf,findIndex等方法也能做去重，就不一一列舉，有興趣的可以自己做一下。

其他

[我的博客，歡迎交流！](http://rattenking.gitee.io/stone/index.html)

[我的CSDN博客，歡迎交流！](https://blog.csdn.net/m0_38082783)

[微信小程序專欄](https://blog.csdn.net/column/details/18335.html)

[前端筆記專欄](https://blog.csdn.net/column/details/18321.html)

[微信小程序實現部分高德地圖功能的DEMO下載](http://download.csdn.net/download/m0_38082783/10244082)

[微信小程序實現MUI的部分效果的DEMO下載](http://download.csdn.net/download/m0_38082783/10196944)

[微信小程序實現MUI的GIT項目地址](https://github.com/Rattenking/WXTUI-DEMO)

[微信小程序實例列表](http://blog.csdn.net/m0_38082783/article/details/78853722)

[前端筆記列表](http://blog.csdn.net/m0_38082783/article/details/79208205)

[游戲列表](http://blog.csdn.net/m0_38082783/article/details/79035621)

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轉載于:https://www.cnblogs.com/linewman/p/9918546.html

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