How to iterate through an array inside an object?

Question

I have a config.json file:

{
  "test": {
    "maths": [
      "core",
      "core2"
    ]
  }
}

In my index.js, I want to access the object 'test', and iterate through each of the maths elements.

I am new to arrays, so still trying to figure out how they work. What is wrong with this approach? (I know it does not work)

var CONFIG = require('./config.json')

var fn = CONFIG.test.maths

fn.forEach(function(value){
console.log(value);
});

Also, what is the correct way of doing this?

You can check this answer; http://stackoverflow.com/a/10167931/2324048 — Ali BARIN, Jun 22 '16 at 12:23
The semicolons are not a problem in this case. I get this error : TypeError: Cannot read property 'maths' of undefined — deeveeABC, Jun 22 '16 at 12:25
Do you have node.js installed? `require` is not a native function, but a function defined in node.js — , Jun 22 '16 at 12:26
I get this error: undefined:1 [object Object] ^ SyntaxError: Unexpected token o — deeveeABC, Jun 22 '16 at 12:28
To require a json file as you're trying to do, it must have the `.json` extension. If not, you'll have to use `JSON.parse(require('fs').readFile('./config.js'))` — Marco Scabbiolo, Jun 22 '16 at 12:31
you can get object by this way also var demo = {"test": {"maths": ["core","core2"]}} $.each(demo,function(key,value){ $.each(value,function(getket,getvalue){ alert(getvalue); }); }); alert(JSON.stringify(demo)); — damon, Jun 22 '16 at 12:35

score 2 · Accepted Answer · edited May 23 '17 at 12:32

Try changing config.js to

module.exports = {
  "test": {
    "maths": [
      "core",
      "core2"
    ]
  }
};

As it stands now - your module doesn't export anything.

Update: if you prefer .json - this method won't work as .json can't be exported (but it can be required in node, see How to parse JSON using Node.js?), it works with .js files as modules. And you'll have to change this part too:

require('./config.js')

Update2: it works as is with index.js

var CONFIG = require('./config')

var fn = CONFIG.test.maths

fn.forEach(function(value){
console.log(value);
});

config.json

{
  "test": {
    "maths": [
      "core",
      "core2"
    ]
  }
}

in my node v5.3.0

score 0 · Answer 2 · answered Jun 22 '16 at 12:34

0

To fix this rename your config.js file to config.json (For naming convention sake)

Change:

var CONFIG = require('./config')

To:

var CONFIG = require('./config.json')

The reason is that requiring a file requires the exact filename including the extension

answered Jun 22 '16 at 12:34

Greg Rebisz

156
7

sorry, I mean my file is called config.json (corrected the question). This does not seem to solve anything – deeveeABC Jun 22 '16 at 12:36

score 0 · Answer 3 · answered Jun 22 '16 at 12:35

3 posible solutions, choose the one that suits you the most:

Change the file extension of config.js , to config.json
Read the file instead and parse it as JSON: var CONFIG = JSON.parse(require('fs').readFile('./config.js'));
Make the file a module that exports the JSON instead of plain JSON, as Anton suggested

score 0 · Answer 4 · answered Jun 22 '16 at 13:11

0

You can simply use the JQuery method getJSON to load the Json into Javascript.

`$.getJSON( "config.json", function( data ) {
   console.log(data);
   var val = data.test.maths
   val.forEach(function (d) {
     console.log(d);
   })
 });`

answered Jun 22 '16 at 13:11

Prakash Thiru

41
5

How to iterate through an array inside an object?

4 Answers4