Check whether a value exists in JSON object

user_803050 0
Viewed 155947

I have the next JSON: 

var JSONObject = {"animals": [{name:"cat"}, {name:"dog"}]};

What is the best way to know if the "dog" value exists in the JSON object?

Thanks.

Solution 1

var JSONObject = {"animals": [{name:"cat"}, {name:"dog"}]};
...
for (i=0; i < JSONObject.animals.length; i++) {
    if (JSONObject.animals[i].name == "dog")
        return true;
}
return false;

Solution 2 (JQuery)

var JSONObject = {"animals": [{name:"cat"}, {name:"dog"}]};
...
$.map(JSONObject.animals, function(elem, index) {
 if (elem.name == "dog") 
     return true;
});
return false;

Solution 3 (using some() method)

function _isContains(json, value) {
    let contains = false;
    Object.keys(json).some(key => {
        contains = typeof json[key] === 'object' ? 
        _isContains(json[key], value) : json[key] === value;
        return contains;
    });
    return contains;
}
json javascript
9 Answers

Why not JSON.stringify and .includes()?

You can easily check if a JSON object includes a value by turning it into a string and checking the string.

console.log(JSON.stringify(JSONObject).includes("dog"))
--> true

Edit: make sure to check browser compatibility for .includes(), and this approach should be used only when the key names are known to not be the search value.

user_45950050

You could improve on the answer from Ponmudi VN:

  • Shorter Code
  • Look for a key and a value

See this fiddle: https://jsfiddle.net/solarbaypilot/sn3wtea2/

function _isContains(json, keyname, value) {

return Object.keys(json).some(key => {
        return typeof json[key] === 'object' ? 
        _isContains(json[key], keyname, value) : key === keyname && json[key] === value;
    });
}

var JSONObject = {"animals": [{name:"cat"}, {name:"dog"}]};


document.getElementById('dog').innerHTML = _isContains(JSONObject, "name", "dog");
document.getElementById('puppy').innerHTML = _isContains(JSONObject, "name", "puppy");
user_32809630 
var JSONObject = {"animals": [{name:"cat"}, {name:"dog"}]};

 var Duplicate= JSONObject .find(s => s.name== "cat");
        if (typeof (Duplicate) === "undefined") {
           alert("Not Exist");
           return;
        } else {
            if (JSON.stringify(Duplicate).length > 0) {
                alert("Value Exist");
                return;
            }
        }
user_139630170

I think this is the best and easy way:

$lista = @()

$lista += ('{"name": "Diego" }' | ConvertFrom-Json)
$lista += ('{"name": "Monica" }' | ConvertFrom-Json)
$lista += ('{"name": "Celia" }' | ConvertFrom-Json)
$lista += ('{"name": "Quin" }' | ConvertFrom-Json)

if ("Diego" -in $lista.name) {
    Write-Host "is in the list"
    return $true

}
else {
    Write-Host "not in the list"
    return $false
}
user_53024610

Because the "dog" you are looking for is inside of an array, then you may also use filter function, which returns always an array of items that much the filter criteria.
If the applied filter returns an empty array then no entries for "dog".

const JSONObject = {"animals": [{name: "cat"}, {name: "dog"}]}; // Your array

const exists = JSONObject.animals.filter(item => item.name === "dog").length > 0;
console.log("Exists? " + exists); // Exists: true

You may also get a count of how many times dog exists in your array.

const JSONObject = {"animals": [{name: "cat"}, {name: "dog"}]}; // Your array

const existsCount = JSONObject.animals.filter(item => item.name === "dog").length;
console.log("Exists: " + existsCount + " time(s)"); // Exists: 1 time(s)
user_11235010
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