javascript - select json object item based on array value

Question

if i have an array of values:

['test1', 'test2', 'test3']

and a json object:

var tester = {'test1' : 'test 1 value', 'test2' : 'test 2 value' }

how can i use the array values as a selector to the json object.

I tried: tester.myarray[0]

but that obviously didnt work.

EDIT:

Additionally, i might need to work with nested values like:

 var myArray = ['test1', 'test2']

 var tester = {'test1' : { 'test2' : 'test 1/2 value'}}

so in this example i have an array, myArray which essentially contains the path of where to find the value in the json object. i.e tester.test1.test2.

I would expect to based on the array be able to find the value in the json object

Importantly, the size of the path is not known up front so i assume i will need to loop over the array values to build the path

What should happen if some value doesn't exist in the object? — thefourtheye
– thefourtheye, Commented Apr 12, 2014 at 14:00
Nope. That is not clear. Can you please show what exactly is your expected output, in both the cases? — thefourtheye
– thefourtheye, Commented Apr 12, 2014 at 14:01

awm · Accepted Answer · 2014-04-12 13:53:35Z

3

I believe this is the expression you're looking for.

tester[myarray[0]]

answered Apr 12, 2014 at 13:53

awm

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2 Comments

Marty Wallace Over a year ago

thank you this works. i edited my question slightly just now (sorry). Just an additional requirement regarding possible nesting

awm Over a year ago

I recommend going over to jsfiddle and trying this stuff out. Constructions such as a[b[c[d]]] and a[b][c][d] are totally fine.

thefourtheye · Accepted Answer · 2014-04-12 14:07:06Z

1

You can use Array.prototype.map to get the corresponding elements from the object

var array1 = ['test1', 'test2', 'test3'],
    tester = {'test1' : 'test 1 value', 'test2' : 'test 2 value' };

console.log(array1.map(function(currentKey) {
    return tester[currentKey];
}));
# [ 'test 1 value', 'test 2 value', undefined ]

Edit: As per your latest edit, if you want to get the data from the nested structure, you can do it with Array.prototype.reduce like this

console.log(myArray.reduce(function(result, current) {
    return result[current];
}, tester));
# test 1/2 value

edited Apr 12, 2014 at 14:07

answered Apr 12, 2014 at 13:54

thefourtheye

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