如何在数组中获取唯一值 [英] How to get unique values in an array

问题描述

如何获取数组中唯一值的列表？我是否总是必须使用第二个数组，或者在JavaScript中是否有类似java的hashmap？

How can I get a list of unique values in an array? Do I always have to use a second array or is there something similar to java's hashmap in JavaScript?

我将使用 JavaScript 和仅 jQuery 。没有额外的库可以使用。

I am going to be using JavaScript and jQuery only. No additional libraries can be used.

推荐答案

因为我在@Rocket答案的评论中继续讨论它，我也可以提供一个不使用库的示例。这需要两个新的原型函数，包含和唯一

Since I went on about it in the comments for @Rocket's answer, I may as well provide an example that uses no libraries. This requires two new prototype functions, contains and unique

Array.prototype.contains = function(v) {
    for(var i = 0; i < this.length; i++) {
        if(this[i] === v) return true;
    }
    return false;
};

Array.prototype.unique = function() {
    var arr = [];
    for(var i = 0; i < this.length; i++) {
        if(!arr.includes(this[i])) {
            arr.push(this[i]);
        }
    }
    return arr; 
}

然后你可以这样做：

var duplicates = [1,3,4,2,1,2,3,8];
var uniques = duplicates.unique(); // result = [1,3,4,2,8]

为了获得更高的可靠性，你可以用MDN的 indexOf shim替换包含并检查每个元素的 indexOf 等于-1： https://developer.mozilla.org/ en / JavaScript / Reference / Global_Objects / Array / indexOf

For more reliability, you can replace contains with MDN's indexOf shim and check if each element's indexOf is equal to -1: https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array/indexOf

这篇关于如何在数组中获取唯一值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！