Revisions to How to check if a string is a valid JSON string?

boolean expressions don't need ternaries to convert to true or false

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edited Mar 3, 2023 at 23:46

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// vanillaJS
function isJSON(str) {
    try {
        return (JSON.parse(str) && !!str);
    } catch (e) {
        return false;
    }
}

Usage: isJSON({}) will be false, isJSON('{}') will be true.

To check if something is an Array or Object (parsed JSON):

// vanillaJS
function isAO(val) {
    return val instanceof Array || val instanceof Object ? true : false;Object;
}

// ES2015
var isAO = (val) => val instanceof Array || val instanceof Object ? true : false;Object;

Usage: isAO({}) will be true, isAO('{}') will be false.

// vanillaJS
function isJSON(str) {
    try {
        return (JSON.parse(str) && !!str);
    } catch (e) {
        return false;
    }
}

Usage: isJSON({}) will be false, isJSON('{}') will be true.

To check if something is an Array or Object (parsed JSON):

// vanillaJS
function isAO(val) {
    return val instanceof Array || val instanceof Object ? true : false;
}

// ES2015
var isAO = (val) => val instanceof Array || val instanceof Object ? true : false;

Usage: isAO({}) will be true, isAO('{}') will be false.

// vanillaJS
function isJSON(str) {
    try {
        return (JSON.parse(str) && !!str);
    } catch (e) {
        return false;
    }
}

Usage: isJSON({}) will be false, isJSON('{}') will be true.

To check if something is an Array or Object (parsed JSON):

// vanillaJS
function isAO(val) {
    return val instanceof Array || val instanceof Object;
}

// ES2015
var isAO = (val) => val instanceof Array || val instanceof Object;

Usage: isAO({}) will be true, isAO('{}') will be false.

marked down properly; added some ES2015; filter for blocking null values in isJSON

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edit approved Aug 24, 2017 at 0:06

Machado

10.1k
6
44
50

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

usage: isJSON({})Usage: isJSON({}) will be falsefalse, isJSON('{}')isJSON('{}') will be truetrue.

or toTo check if something is an ArrayArray or ObjectObject (parsedparsed JSON):

// vanillaJS
function isAO(strval) {
    if(strreturn val instanceof Array || strval instanceof Object) {return? true : false;
} 

// ES2015
var isAO = return(val) false
}=> val instanceof Array || val instanceof Object ? true : false;

usage: isAO({})Usage: isAO({}) will be true true, isAO('{}')isAO('{}') will be falsefalse.

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

usage: isJSON({}) will be false, isJSON('{}') will be true

or to check if something is an Array or Object (parsed JSON)

function isAO(str) {
    if(str instanceof Array || str instanceof Object) {return true}
    return false
}

usage: isAO({}) will be true , isAO('{}') will be false

// vanillaJS
function isJSON(str) {
    try {
        return (JSON.parse(str) && !!str);
    } catch (e) {
        return false;
    }
}

Usage: isJSON({}) will be false, isJSON('{}') will be true.

To check if something is an Array or Object (parsed JSON):

// vanillaJS
function isAO(val) {
    return val instanceof Array || val instanceof Object ? true : false;
} 

// ES2015
var isAO = (val) => val instanceof Array || val instanceof Object ? true : false;

Usage: isAO({}) will be true, isAO('{}') will be false.

Fix indentation

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edited Feb 7, 2017 at 10:33

Rawa

13.8k
7
41
56

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

usage: isJSON({}) will be false, isJSON('{}') will be true

or to check if something is an Array or Object (parsed JSON)

function isAO(str) {
    if(str instanceof Array || str instanceof Object) {return true}
    return false
}

usage: isAO({}) will be true , isAO('{}') will be false

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

usage: isJSON({}) will be false, isJSON('{}') will be true

or to check if something is an Array or Object (parsed JSON)

function isAO(str) {
    if(str instanceof Array || str instanceof Object) {return true}
    return false
}

usage: isAO({}) will be true , isAO('{}') will be false

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

usage: isJSON({}) will be false, isJSON('{}') will be true

or to check if something is an Array or Object (parsed JSON)

function isAO(str) {
    if(str instanceof Array || str instanceof Object) {return true}
    return false
}

usage: isAO({}) will be true , isAO('{}') will be false

No need to be racist.

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edit approved Mar 18, 2016 at 19:57

HaloWebMaster

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6
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added 7 characters in body

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edited Aug 28, 2015 at 19:39

moeiscool

1.4k
12
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added 9 characters in body

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edited Aug 28, 2015 at 19:32

moeiscool

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created Aug 28, 2015 at 19:22

moeiscool

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