JS implements the function of removing duplicate items in an array

This article mainly introduces the object-based features of JS to achieve the function of removing duplicate items in the array. It analyzes in detail the specific steps and related operation skills of JS to implement array deduplication based on the uniqueness of key values ​​in the form of examples. Friends who need it can For reference, I hope it can help everyone.

The example in this article describes the object-based feature of JS to achieve the function of removing duplicate items in an array. I would like to share it with you for your reference. The details are as follows:

There are many methods for deduplicating arrays, and different methods have different efficiencies. For example, in the previous article, the summary of the array deduplication algorithm implemented by JS summarized and analyzed 4 implementation methods. Here we introduce an efficient array deduplication method: a method to remove duplicate items in an array based on the characteristics of JS objects.

1. Characteristics of JS objects (characteristics used in this article): key is always unique

Example: Explain the uniqueness of object key value property, that is, when reassigning an existing property in js, the key is actually overwritten instead of creating a new key

var t={name:'张三',age:20};//定义个js对象
console.log(t.name);//控制台输出：张三
//注意:此时对象t有两个属性：name、age
t.name='李四';
console.log(t.name);//控制台输出：李四
//注意:此时对象t依然有两个属性：name、age

2. Array deduplication step analysis

is divided into two steps:

1. Convert the deduplicated array into a js object and return it. Conversion rules: change the value in the array into the key in the js object, and then give the value to any value;

2. Restore the object in step 1 to an array, the key of the object as an element in an array.

3. Array deduplication implementation

var arr=[1,2,3,4,5,23,4,2,4,3];
//1.把数组装换成对象，数组的元素作为对象的key，然后返回对象
function toObject(ac_array){
    var obj={};//私有的对象
    for (var i=0;i<ac_array.length;i++) {
      obj[ac_array[i]] = true;
    }
    console.log(obj);//Object {1: true, 2: true, 3: true, 4: true, 5: true, 23: true}
    return obj;
}
//2.把对象的key获取出来作为数组的元素，然后返回数组
function keys(ac_obj){
    var arr = [];
    for(var item in ac_obj){
      if(ac_obj.hasOwnProperty(item)){
        arr.push(item);
      }
    }
    console.log(arr);//["1", "2", "3", "4", "5", "23"]
    return arr;
}
//综合
function uniq(ac_array){
    return keys(toObject(ac_array));
}
//测试
var uniq_array=uniq(arr);
console.log(uniq_array);//["1", "2", "3", "4", "5", "23"]

Code test results:

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