how to load json in file into variable

Question

I have a file.json with contents:

{
  "a":{"var1":"Sábado"},
  "b":{"var2":"Domingo"}
}

Having in mind that I cannot edit file.js, I need to figure out a way to load the json contained in that file into a variable mj, so that alert(mj["a"].var1) shows me the message Sábado.

UPDATE: Is this possible to accomplish without using JQuery, Prototype, or any other js library?

Are you using node.js, or is this supposed to run in a browser ? — lmjohns3
– lmjohns3, Commented Aug 17, 2013 at 23:07
If you are using JQuery you can do api.jquery.com/jQuery.getJSON — digidigo
– digidigo, Commented Aug 17, 2013 at 23:09
BTW, the name file.js is ambiguous, it should be file.json — Nabil Kadimi
– Nabil Kadimi, Commented Aug 17, 2013 at 23:17
I edited the question and file name. It has to be a solution that does not use JQuery, node.js or other js library — dev4life
– dev4life, Commented Aug 17, 2013 at 23:19

technosaurus · Accepted Answer · 2013-08-18 06:16:12Z

1

This is plain js,(with no use of eval) and should even work cross domain:

var script = document.createElement('script');
script.type = 'text/javascript';
script.src = "file.js"; /*url of your js/jsonp file */
var head = document.getElementsByTagName('head')[0];
head.insertBefore(script, head.firstChild);

edited Aug 18, 2013 at 6:16

answered Aug 18, 2013 at 5:06

technosaurus

7,8621 gold badge33 silver badges53 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

dev4life Over a year ago

ok, you have loaded the json file, but how do you store the contents of the json file in variable mj?

technosaurus Over a year ago

you wouldn't need mj (unless you are the Chicago Bulls:), just alert(a.var1)... however may be problematic if you have globals (or local variables) called a, b, ... that match the json.

Jonathan Lonowski Over a year ago

This would work great if the file was formatted for JSONP. But, without the padding, {...} will be parsed as a block, making : unexpected after a String.

technosaurus Over a year ago

good point, last time I used this with unmodifyable data I had to either wrapped the data in a callback() or prepended it with a someVar= server side ... the basic proxy was something like echo $HEADERSTUFF; printf "mj=";cat $THEFILE (or wget -O - $THEURL if the file was remote)

brian d foy · Accepted Answer · 2013-12-07 14:21:00Z

0

You make a normal ajax request to the file.json using XMLHttpRequest object. In the onreadystatechange function write your eval logic to receive the json and assign into variable.

It the eval statement would look like

var data = eval ('(' + xhr.responseText + ')');

Go through the following pages if you aren't sure how to work with ajax: http://www.w3schools.com/ajax/default.asp

Edit: Jonathan's answer seems to be a recommended approach; that answer didn't come to my mind at the time. Use JSON.parse() instead of eval().

var data = JSON.parse(xhr.responseText);

edited Dec 7, 2013 at 14:21

brian d foy

134k31 gold badges214 silver badges613 bronze badges

answered Aug 18, 2013 at 0:35

deostroll

12k22 gold badges94 silver badges168 bronze badges

1 Comment

Jonathan Lonowski Over a year ago

This seems like one of those examples that contributed to w3fools. eval() isn't necessary for this. Use JSON.parse().

Roger Barreto · Accepted Answer · 2013-08-17 23:33:28Z

0

Well, the easiest thing that crossed my mind is to create an iframe with the source to json and on the load event access it's content with javascript to assign in a variable, or implement by hand what a common JSFramework would do...

answered Aug 17, 2013 at 23:33

Roger Barreto

2,2841 gold badge19 silver badges24 bronze badges

Collectives™ on Stack Overflow

how to load json in file into variable

3 Answers 3

4 Comments

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

4 Comments

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related