How to check if a json string is valid or not in JavaScript or Jquery?

Question

Have tried :

function isJSON(str) {
    try {
        JSON.parse(str);
    } catch (e) {
        return false;
    }
    return true;
}

To check weather a string is json or not. It returns true for boolean type formats.

Is there any possible way to identify a valid json string in Java Script or in JQuery?

what do you mean by boolean type formats? – Daniel A. White Aug 16 '16 at 10:16 — Daniel A. White, Aug 16 '16 at 10:16
He means `isJSON(false)` returns `true`. – Jeremy Thille Aug 16 '16 at 10:17 — Jeremy Thille, Aug 16 '16 at 10:17
Yeah you were right Jeremy Thille – Tom Taylor Aug 16 '16 at 11:03 — Tom Taylor, Aug 16 '16 at 11:03

Simone Poggi · Accepted Answer · 2016-08-16T14:00:05.763

8

To assure you have a valid json you must have a string first

function isJSON(str) {

    if( typeof( str ) !== 'string' ) { 
        return false;
    }
    try {
        JSON.parse(str);
        return true;
    } catch (e) {
        return false;
    }
}

edited Aug 16 '16 at 14:00

answered Aug 16 '16 at 10:19

Simone Poggi

1,348
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score 2 · Answer 2 · answered Aug 16 '16 at 10:18

Your function works, just add a boolean check :

function isJSON(str) {

    if(typeof(str) === "boolean"){ return false; } // or if(typeof(str) !== "string")

    try {
        JSON.parse(str);
    } catch (e) {
        return false;
    }
    return true;
}

How to check if a json string is valid or not in JavaScript or Jquery?

2 Answers2