與hasOwnProperty刪除重複

Question

讓我們說我們有一個對象：

message { 
    diff: { 
    cat: "Tabby" 
    name: "Meow Meow" 
    } 
} 

你可以檢查與hasOwnProperty（一式兩份），做一個去除重複的？示例

for (key in message.diff) { 
    //outputs every change when all keys are updated 
    if (message.diff.hasOwnProperty(key)){ 
    this.uniqueArray.push(key); 
    } 
} 

編輯：我意識到可能有混淆，我想談談。 我有監聽任何形式的元件，其可以被更新，其記錄了輸入到控制檯的功能。它主要是傾聽屬性名稱。這將輸出到可能包含或不包含名稱重複的數組。

如果我們的表單字段很多很多次更新，就變成：

Current Output: ['name', 'name', 'name', 'cat'] 
Desired Ouput: ['name', 'cat'] 

Answer 1

您可以使用Object.keys()，Array.prototype.filter()，Array.prototype.includes()以檢查是否對象的屬性是數組，Array.prototype.push()的元素，擴散元件

var message = { 
 
    diff: { 
 
    cat: "Tabby", 
 
    name: "Meow Meow" 
 
    } 
 
} 
 

 
var arr = ["name", "cat"]; 
 

 
arr.push(...Object.keys(message.diff).filter(function(diff) {return !arr.includes(diff)})); 
 

 
console.log(arr); 
 

 
var message = { 
 
    diff: { 
 
    lion: "Tabby", 
 
    tiger: "Meow Meow" 
 
    } 
 
} 
 

 
arr.push(
 
    ...Object.keys(message.diff) 
 
    .filter(function(diff) {return !arr.includes(diff)})) 
 

 
console.log(arr);

Answer 2

檢查對象項不存在數組

for (key in message.diff) { 
    //outputs every change when all keys are updated 
    if (message.diff.hasOwnProperty(key) && this.uniqueArray.indexOf(key) == -1){ 
    this.uniqueArray.push(key); 
    } 
}