How can I get the index from a JSON object with value?

Question

This is my JSON string.

[{
    "name": "placeHolder",
    "section": "right"
}, {
    "name": "Overview",
    "section": "left"
}, {
    "name": "ByFunction",
    "section": "left"
}, {
    "name": "Time",
    "section": "left"
}, {
    "name": "allFit",
    "section": "left"
}, {
    "name": "allbMatches",
    "section": "left"
}, {
    "name": "allOffers",
    "section": "left"
}, {
    "name": "allInterests",
    "section": "left"
}, {
    "name": "allResponses",
    "section": "left"
}, {
    "name": "divChanged",
    "section": "right"
}]

Now, I have the value allInterests and I want to find out the index (this case; it is '7') of this object in the above string. I tried the following code, but it always returns -1.

var q = MY_JSON_STRING
console.log(q.indexOf( 'allInterests' ) );

What you posted is a plain old JavaScript array, not a JSON string. Array.prototype.indexOf() isn't doing what you think it is. — Ted Hopp
– Ted Hopp, Commented Apr 5, 2016 at 7:01

cflinspach · Accepted Answer · 2022-01-07 00:55:13Z

50

You will have to use Array.find or Array.filter or Array.forEach.

Since your value is array and you need the position of the element, you will have to iterate over it.

Array.find

var data = [{"name":"placeHolder","section":"right"},{"name":"Overview","section":"left"},{"name":"ByFunction","section":"left"},{"name":"Time","section":"left"},{"name":"allFit","section":"left"},{"name":"allbMatches","section":"left"},{"name":"allOffers","section":"left"},{"name":"allInterests","section":"left"},{"name":"allResponses","section":"left"},{"name":"divChanged","section":"right"}];
var index = -1;
var val = "allInterests"
var filteredObj = data.find(function(item, i){
  if(item.name === val){
    index = i;
    return i;
  }
});

console.log(index, filteredObj);

Array.findIndex() @Ted Hopp's suggestion

var data = [{"name":"placeHolder","section":"right"},{"name":"Overview","section":"left"},{"name":"ByFunction","section":"left"},{"name":"Time","section":"left"},{"name":"allFit","section":"left"},{"name":"allbMatches","section":"left"},{"name":"allOffers","section":"left"},{"name":"allInterests","section":"left"},{"name":"allResponses","section":"left"},{"name":"divChanged","section":"right"}];

var val = "allInterests"
var index = data.findIndex(function(item, i){
  return item.name === val
});

console.log(index);

Default Array.indexOf() will match searchValue to current element and not its properties. You can refer Array.indexOf - polyfill on MDN

edited Jan 7, 2022 at 0:55

cflinspach

3201 gold badge4 silver badges18 bronze badges

answered Apr 5, 2016 at 7:00

Rajesh Dixit

25.1k5 gold badges52 silver badges86 bronze badges

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

2 Comments

Ted Hopp Over a year ago

It would make more sense to use Array.findIndex() since OP wants the index of an element.

Rajesh Dixit Over a year ago

You are correct, but I assumed, OP would access object after fetching index, so used Array.find

double-beep · Accepted Answer · 2021-01-02 09:19:29Z

27

You can use Array.findIndex.

var data= [{
  "name": "placeHolder",
  "section": "right"
}, {
  "name": "Overview",
  "section": "left"
}, {
  "name": "ByFunction",
  "section": "left"
}, {
  "name": "Time",
  "section": "left"
}, {
  "name": "allFit",
  "section": "left"
}, {
  "name": "allbMatches",
  "section": "left"
}, {
  "name": "allOffers",
  "section": "left"
}, {
  "name": "allInterests",
  "section": "left"
}, {
  "name": "allResponses",
  "section": "left"
}, {
  "name": "divChanged",
  "section": "right"
}];
var index = data.findIndex(obj => obj.name=="allInterests");

console.log(index);

edited Jan 2, 2021 at 9:19

double-beep

5,67019 gold badges43 silver badges50 bronze badges

answered Dec 1, 2017 at 10:41

Sarat Chandra

6,18838 silver badges34 bronze badges

Comments

void · Accepted Answer · 2016-04-05 07:05:26Z

4

Traverse through the array and find the index of the element which contains a key name and has the value as the passed param.

var data = [{
  "name": "placeHolder",
  "section": "right"
}, {
  "name": "Overview",
  "section": "left"
}, {
  "name": "ByFunction",
  "section": "left"
}, {
  "name": "Time",
  "section": "left"
}, {
  "name": "allFit",
  "section": "left"
}, {
  "name": "allbMatches",
  "section": "left"
}, {
  "name": "allOffers",
  "section": "left"
}, {
  "name": "allInterests",
  "section": "left"
}, {
  "name": "allResponses",
  "section": "left"
}, {
  "name": "divChanged",
  "section": "right"
}];

Array.prototype.getIndexOf = function(el) {

  var arr = this;

  for (var i=0; i<arr.length; i++){
     console.log(arr[i].name);
     if(arr[i].name==el){
       return i;
     }
     
  }
  
  return -1;

}

alert(data.getIndexOf("allResponses"));

answered Apr 5, 2016 at 7:05

void

36.8k10 gold badges72 silver badges111 bronze badges

1 Comment

Ted Hopp Over a year ago

Why reinvent the wheel. There's already Array.prototype.findIndex that does the same job as your getIndexOf.

Jesús Gabriel Banda Durán · Accepted Answer · 2019-09-20 05:17:21Z

In all previous solutions, you must know the name of the attribute or field. A more generic solution for any attribute is this:

let data = 
[{
    "name": "placeHolder",
    "section": "right"
}, {
    "name": "Overview",
    "section": "left"
}, {
    "name": "ByFunction",
    "section": "left"
}, {
    "name": "Time",
    "section": "left"
}, {
    "name": "allFit",
    "section": "left"
}, {
    "name": "allbMatches",
    "section": "left"
}, {
    "name": "allOffers",
    "section": "left"
}, {
    "name": "allInterests",
    "section": "left"
}, {
    "name": "allResponses",
    "section": "left"
}, {
    "name": "divChanged",
    "section": "right"
}]    

function findByKey(key, value) {
    return (item, i) => item[key] === value
}

let findParams = findByKey('name', 'allOffers')
let index = data.findIndex(findParams)

GMKHussain · Accepted Answer · 2019-04-11 06:14:50Z

Function base solution for get index from a JSON object with value by VanillaJS.

Exemple: https://codepen.io/gmkhussain/pen/mgmEEW

    var data= [{
      "name": "placeHolder",
      "section": "right"
    }, {
      "name": "Overview",
      "section": "left"
    }, {
      "name": "ByFunction",
      "section": "left"
    }, {
      "name": "Time",
      "section": "left"
    }, {
      "name": "allFit",
      "section": "left"
    }, {
      "name": "allbMatches",
      "section": "left"
    }, {
      "name": "allOffers",
      "section": "left"
    }, {
      "name": "allInterests",
      "section": "left"
    }, {
      "name": "allResponses",
      "section": "left"
    }, {
      "name": "divChanged",
      "section": "right"
    }];
    
    
    // create function
    function findIndex(jsonData, findThis){
      var indexNum = jsonData.findIndex(obj => obj.name==findThis);  

    //Output of result
          document.querySelector("#output").innerHTML=indexNum;
          console.log("🍇 Array Index number: " + indexNum + " , value of " + findThis );
    }
    
    
    /* call function */
    findIndex(data, "allOffers");

Output of index number : <h1 id="output"></h1>

deHaar · Accepted Answer · 2019-07-28 19:51:19Z

0

Once you have a json object

obj.valueOf(Object.keys(obj).indexOf('String_to_Find'))

edited Jul 28, 2019 at 19:51

deHaar

18.7k11 gold badges48 silver badges57 bronze badges

answered Jul 28, 2019 at 19:32

Saurav

113 bronze badges

Comments

sahba · Accepted Answer · 2022-07-20 21:59:28Z

0

var MYarry=["13","18","77","4543"];
for (var i=0;i<=MYarry.length;i++){
           if(MYarry[i] === "18") {
           console.log(i);
           }
        }

answered Jul 20, 2022 at 21:59

sahba

394 bronze badges

Collectives™ on Stack Overflow

How can I get the index from a JSON object with value?

7 Answers 7

Array.find

Array.findIndex() @Ted Hopp's suggestion

2 Comments

Comments

1 Comment

Comments

Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

7 Answers 7

Array.find

Array.findIndex() @Ted Hopp's suggestion

2 Comments

Comments

1 Comment

Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related