Unable to display array content

Question

        var dataHolder = [
        {
            "letterA" : "Fruits",
            "letterB" : "Veges",
            "letterC" : "Meat"
        }
    ];
    console.log(dataHolder[0].letterA);
    var result = "";
    function getData(myLetter) {
        for (var i = 0; i < dataHolder.length; i++) {
           if(dataHolder[i][myLetter] === myLetter){
               console.log(dataHolder[i][myLetter]);
           }
           else{
               console.log("No data found");
           }
            }
        }
    getData("letterA");

This is my code and i'm just trying to match the content of the array with the passed parameter, but every time it's giving No data found as output and not the matching content, it seems i'm missing something very basic here. Any help would be highly appreciated.Thanks!!

You are comparing the value in the key. For example if you call getData("letterA") the comparison will be between Fruits and letterA. — Giorgio Catenacci
– Giorgio Catenacci, Commented Jul 6, 2017 at 11:20
It is a json object use json functions like json.hasOwnProperty(key) to achieve your goal. — Osama
– Osama, Commented Jul 6, 2017 at 11:25

prasanth · Accepted Answer · 2017-07-06 11:38:51Z

2

You matching was wrong. you are matching the letters == fruites .You should check is the key exist or not ,that's enough using hasOwnProperty()

Check this below. i was mention the error

var dataHolder = [{
  "letterA": "Fruits",
  "letterB": "Veges",
  "letterC": "Meat"
}];

var result = "";

function getData(myLetter) {
  for (var i = 0; i < dataHolder.length; i++) {
  console.log('this is the pblm  '+dataHolder[i][myLetter] +' != '+myLetter)
     if (dataHolder[i].hasOwnProperty(myLetter)) {
      console.log(dataHolder[i][myLetter]);
    } else {
      console.log("No data found");
    }
  }
}
getData("letterA");

For your way use with for...in

var dataHolder = [{
  "letterA": "Fruits",
  "letterB": "Veges",
  "letterC": "Meat"
}];

var result = "";

function getData(myLetter) {
  for (var i in dataHolder) {
    if (dataHolder[i].hasOwnProperty(myLetter)) {
      console.log(dataHolder[i][myLetter]);
    } else {
      console.log("No data found");
    }
  }
}
getData("letterA")

edited Jul 6, 2017 at 11:38

answered Jul 6, 2017 at 11:18

prasanth

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3 Comments

MarcoL Over a year ago

This works as long as the value of dataHolder[i][myLetter] is truthy. I'd probably tweak it a bit to use either the in operator o the hasOwnProperty method.

MarcoL Over a year ago

myLetter in dataHolder[i]

Daniel Manta Over a year ago

With this change you can find values like null, undefined, "", which where previously considered "no data" even when property existed. Okay, but not sure for what this can be useful.

Dinesh undefined · Accepted Answer · 2017-07-06 11:21:26Z

You are comparing value with key that is wrong.

The hasOwnProperty() method returns a boolean indicating whether the object has the specified property as own (not inherited) property.

Use hasOwnProperty to check key exists or not.

dataHolder[i].hasOwnProperty(myLetter)

var dataHolder = [
        {
            "letterA" : "Fruits",
            "letterB" : "Veges",
            "letterC" : "Meat"
        }
    ];
   
    var result = "";
    function getData(myLetter) {
        for (var i = 0; i < dataHolder.length; i++) {
       
           if(dataHolder[i].hasOwnProperty(myLetter)){
               console.log(dataHolder[i][myLetter]);
           }
           else{
               console.log("No data found");
           }
            }
        }
    getData("letterA");

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