双层循环，外层循环元素，内层循环时比较值
如果有相同的值则跳过，不相同则push进数组
Array.prototype.distinct = function(){var arr = this,
result = [],
i,
j,
len = arr.length;for(i = 0; i < len; i++){for(j = i + 1; j < len; j++){if(arr[i] === arr[j]){
j = ++i;
}
}
result.push(arr[i]);
}return result;
}var arra = [1,2,3,4,4,1,1,2,1,1,1];
arra.distinct(); //返回[3,4,2,1]双层循环，外层循环元素，内层循环时比较值
值相同时，则删去这个值
注意点:删除元素之后，需要将数组的长度也减1.
Array.prototype.distinct = function (){var arr = this,
i,
j,
len = arr.length;for(i = 0; i < len; i++){for(j = i + 1; j < len; j++){if(arr[i] == arr[j]){
arr.splice(j,1);
len--;
j--;
}
}
}return arr;
};var a = [1,2,3,4,5,6,5,3,2,4,56,4,1,2,1,1,1,1,1,1,];var b = a.distinct();
console.log(b.toString()); //1,2,3,4,5,6,56优点：简单易懂
缺点：占用内存高，速度慢
Array.prototype.distinct = function (){var arr = this,
i,
obj = {},
result = [],
len = arr.length;for(i = 0; i< arr.length; i++){if(!obj[arr[i]]){ //如果能查找到，证明数组元素重复了obj[arr[i]] = 1;
result.push(arr[i]);
}
}return result;
};var a = [1,2,3,4,5,6,5,3,2,4,56,4,1,2,1,1,1,1,1,1,];var b = a.distinct();
console.log(b.toString()); //1,2,3,4,5,6,56运用递归的思想
先排序，然后从最后开始比较，遇到相同，则删除
Array.prototype.distinct = function (){var arr = this,
len = arr.length;
arr.sort(function(a,b){ //对数组进行排序才能方便比较return a - b;
})function loop(index){if(index >= 1){if(arr[index] === arr[index-1]){
arr.splice(index,1);
}
loop(index - 1); //递归loop函数进行去重 }
}
loop(len-1);return arr;
};var a = [1,2,3,4,5,6,5,3,2,4,56,4,1,2,1,1,1,1,1,1,56,45,56];var b = a.distinct();
console.log(b.toString()); //1,2,3,4,5,6,45,56indexOf以及forEach
Array.prototype.distinct = function (){var arr = this,
result = [],
len = arr.length;
arr.forEach(function(v, i ,arr){ //这里利用map，filter方法也可以实现var bool = arr.indexOf(v,i+1); //从传入参数的下一个索引值开始寻找是否存在重复if(bool === -1){
result.push(v);
}
})return result;
};var a = [1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,3,3,3,3,3,3,3,2,3,3,2,2,1,23,1,23,2,3,2,3,2,3];var b = a.distinct();
console.log(b.toString()); //1,23,2,3Set数据结构，它类似于数组，其成员的值都是唯一的。
利用Array.from将Set结构转换成数组
function dedupe(array){return Array.from(new Set(array));
}
dedupe([1,1,2,3]) //[1,2,3]拓展运算符(...)内部使用for...of循环
let arr = [1,2,3,3]; let resultarr = [...new Set(arr)]; console.log(resultarr); //[1,2,3]
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