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Update array.js #2

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Update array.js #2

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36 changes: 21 additions & 15 deletions js/array.js
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Original file line number Diff line number Diff line change
Expand Up @@ -71,19 +71,7 @@ function arrayFilterTest() {
* @param : <Array> target 要去重的数组
* @description : 数组去重；可用es6 set、正则、sort等实现
*/
function arrayUnique(target) {
// 纯数组硬比较方式，这里要注意是否需要空对象{}的去重，暂不处理
// var result = [target[0]];
// for (var i = 1, targetLen = target.length; i < targetLen; i++) {
// for (var j = 0, resultLen = result.length; j < resultLen; j++) {
// if (result[j] === target[i]) {
// break; // j++是在循环体结束后自增，使用break则在自增前就跳出循环了
// }
// }
// if (j === resultLen) {
// result.push(target[i]);
// }
// }
/*function arrayUnique(target) {

// 对于去重这种无序的集合，可使用js对象的哈希特性来提高效率，但无法直接区分数字、字符，统一转为字符了
// Note: 数据量少的情况下，哈希算法本身的复杂度就超过了循环对比，所以性能上反而更差
Expand All @@ -100,11 +88,29 @@ function arrayUnique(target) {
}
}
return result;
}
*/
function arrayUnique(target) {
var result = [target[0]];
var temp = Object.create(null);
temp[target[0]] = {};
temp[target[0]][(typeof target[0])] = true
for (var i = 1, targetLen = target.length; i < targetLen; i++) {
if(typeof temp[target[i]] === 'undefined'){
result.push(target[i]);
temp[target[i]] = {};
temp[target[i]][(typeof target[i])] = true
} else if (!(typeof target[i] in temp[target[i]])) {
result.push(target[i]);
temp[target[i]][(typeof target[i])] = true
}
}
return result;
}
function arrayUniqueTest() {
// var target = [1, 2, 3, 3, '3', '3', 'length', '__proto__', 'prototype', true, false, true, {}, {}, null, null];
var target = [1, 2, 3, 3, '3', '3', '__proto__', '__proto__', '__proto__', 'prototype', 'prototype', true, false, true, {}, {}, null, null];
// var target = [1, '1', true, 'true'];
// var target = [1, 2, 3, 3, '3', '3', '__proto__', '__proto__', '__proto__', 'prototype', 'prototype', true, false, true, {}, {}, null, null];
var target = ['1',1,'1',1] //原作者的去重函数在这种情况下无法去重
console.log('\narrayUnique test:\n', arrayUnique(target));
}

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