Add a new object to an existing object. Javascript

Question

I have read SO and others but more complex For referrence:

let newpage = {
  page_no_3: {
    data1: [{index: 1, text: "test1"}],
    data2: [{index: 1, text: "test2"}],
  }
}

What I want to happen when I add new object:

let newpage = {
  page_no_3: {
    data1: [{index: 1, text: "test2"}, {index: 2, text: "test3"}, ...]
    data2: [{index: 1, text: "test2"}, {index: 2, text: "test4"}, ...]
  }
}

NOTE: Sorry it should not be an array but an object.

NOTE2: Sorry again. it should be Array with objects as elements.

PS: When I try to get the data of data1 before inserting, it is giving me an undefined error. I tried it like this:

let page_no = 'page_no_3'
if (nextpage.length == 0) {
    ///
} else { // Both undefined
    console.log(nextpage[page_no].data1)
    console.log(nextpage["page_no_3"].data1)
}

But if I only console.log(nextpage[page_no]) I can see the {index: 1, text: "test2"}.

What do you mean by "add array1[2]1 in data 1? Do you want to convert data 1 into an array? Also, you cannot have spaces in keys in your object, unless you enclosed them in quotes. — Terry
– Terry, Commented Jun 23, 2021 at 7:22
Can you please show a real reference, the pseudo-reference is not accurate enough. — Teemu
– Teemu, Commented Jun 23, 2021 at 7:25
If I understand correctly what you want probably this newpage["page_no_3"].data1 = array1[2] works for you — Alireza Ahmadi
– Alireza Ahmadi, Commented Jun 23, 2021 at 7:29
sorry if I added a space in data and 1. no there are no spaces — rod james
– rod james, Commented Jun 23, 2021 at 7:31

Alois Christen · Accepted Answer · 2021-06-23 08:01:35Z

0

First check that your array exist :

if(newpage["page_no_3"].data1 === undefined){
   newpage["page_no_3"].data1 = [];
}

Then you can add a new object to data1 :

newpage["page_no_3"].data1.push(myAwesomeObject);

maybe this can help you to understand the difference between arrays and objects

answered Jun 23, 2021 at 8:01

Alois Christen

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3 Comments

rod james Over a year ago

Thank you for posting an answer. However, I did try newpage["page_no_3"].data1 and newpage[page_no].data1 but it is giving me a Cannot read property of undefined.

Alois Christen Over a year ago

is newpage defined ? is newpage["page_no_3"] defined ? You need to define everything before using it, newpage and the properties you want to access (here "page_no_3")

rod james Over a year ago

yes. everything is defined before the if else here.

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