Callback for find not working-Javascript

Question

I have written a custom callback function for Javascript's find function but that is always yielding undefined

var objectsArray = [
  { 'a': 1, 'b': 2, 'c': 3 },
  { 'a': 41, 'b': 5, 'c': 7 },
  { 'a': 9, 'b': 2, 'c': 3 },
  { 'a': 4, 'b': 5, 'c': 99 }
];

function mytestMatchesProp(inputKey,val){
    let matchFunc = function(element,index,array){
      Object.keys(element).every(function(key){
          let val1 = (key==inputKey) && (element[key] == val)
          return val1
      })
    }
    return matchFunc
}

let res = objectsArray.find(mytestMatchesProp('a',9))
 console.log('output',res)

I have added a running snippet, any suggestion would be helpful. Maybe i am missing something minor

Nina Scholz · Accepted Answer · 2016-11-22 07:19:02Z

4

You could just return the function for the callback with the right check without key iteration.

var objectsArray = [
  { 'a': 1, 'b': 2, 'c': 3 },
  { 'a': 41, 'b': 5, 'c': 7 },
  { 'a': 9, 'b': 2, 'c': 3 },
  { 'a': 4, 'b': 5, 'c': 99 }
];

function mytestMatchesProp(inputKey, val){
    return function(element, index, array){
        return inputKey in element && element[inputKey] === val;
    };
}

let res = objectsArray.find(mytestMatchesProp('a', 9));
console.log('output', res);

answered Nov 22, 2016 at 7:19

Nina Scholz

388k26 gold badges367 silver badges417 bronze badges

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

Comments

Suren Srapyan · Accepted Answer · 2016-11-22 07:26:10Z

2

You need to change every to some for first, because the every will always return false and also return the result of Object.keys(element).some.... And can simplify.

But I can suggest you more simple code, you only need to check if the property is in the object and it's value is the val, with using lambdas

var objectsArray = [
  { 'a': 1, 'b': 2, 'c': 3 },
  { 'a': 41, 'b': 5, 'c': 7 },
  { 'a': 9, 'b': 2, 'c': 3 },
  { 'a': 4, 'b': 5, 'c': 99 }
];

function mytestMatchesProp(inputKey,val){
    return (element,index,array) => inputKey in element && element[inputKey] === val;
}

let res = objectsArray.find(mytestMatchesProp('a',9))
 console.log('output',res)

edited Nov 22, 2016 at 7:26

answered Nov 22, 2016 at 7:18

Suren Srapyan

68.9k14 gold badges128 silver badges119 bronze badges

1 Comment

Gyanesh Gouraw Over a year ago

Thanks for the explanation

Collectives™ on Stack Overflow

Callback for find not working-Javascript

2 Answers 2

Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related