I have an object array created and it's like this:

for(var i =0; i < this.test.length; i ++){
    var header = this.test[i].hdr;
    var insertData = [];

    switch(header){
        case 'date':
            insertData =  {date: "date"};
            break;
        case 'name':
            insertData =  {name: "name"};
            break;
        case 'age':
            insertData =  {age: "age"};
            break;
        case 'add':
            insertData =  {add: "add"};
            break;
    }
    this.hdrtxt.push(insertData);
}

Now, when I try to get the keys of the object, I used this:

Object.keys(this.hdrtxt);

The result is:

(4) ["0", "1", "2", "3"]

But the output I want is this:

(4) ["date", "name", "age", "add"]

I'm sorry I'm just new to this. How can I attain my goal?

I have an object array created and it's like this:

for(var i =0; i < this.test.length; i ++){
    var header = this.test[i].hdr;
    var insertData = [];

    switch(header){
        case 'date':
            insertData =  {date: "date"};
            break;
        case 'name':
            insertData =  {name: "name"};
            break;
        case 'age':
            insertData =  {age: "age"};
            break;
        case 'add':
            insertData =  {add: "add"};
            break;
    }
    this.hdrtxt.push(insertData);
}

Now, when I try to get the keys of the object, I used this:

Object.keys(this.hdrtxt);

The result is:

(4) ["0", "1", "2", "3"]

But the output I want is this:

(4) ["date", "name", "age", "add"]

I'm sorry I'm just new to this. How can I attain my goal?

• javascript
• arrays
• object

• How are you calling Object.keys(this.hdr)? .hdr looks like a property of each object in the this.test array. – achacttn Commented Dec 7, 2018 at 1:47
• @achacttn Opppss updated. Variable name typo :) – Eem Jee Commented Dec 7, 2018 at 1:54

2 Answers 2

You can use Object.keys with Object.assign and spread the data into one object to get all the keys:

const data = [{ date: "date" }, { name: "name" }, { age: "age" }, { add: "add" }]

const result = Object.keys(Object.assign({}, ...data))

console.log(result)

The main reason for this is due to the fact that you are dealing with an array and Object.keys expects an object to work.

First off that could be done much easier in a reduce

const test = [{hdr: "date"}, {hdr: "name"}, {hdr: "age"}, {hdr: "add"}];

const results = test.reduce((result, item) => [...result, { [item.hdr]: item.hdr }], []);

// This logs, ["0", "1", "2", "3"] because it is an array and the keys are integers.
console.log(Object.keys(results));

// If you want the object keys for each item in the array try mapping each item in the array to it's first key in the keys for that item
console.log(results.map(item => Object.keys(item)[0]));