Find object in array and change its property if I know its other property

Question

I\'ve got an array of objects and I need a function that finds object an array by the objects property (id in example) and changes its other property (name

Answer 1

Use this instead of filter. Filter produce new array.

arrayOfObjects.forEach(function(v){
  if (v.id == id) {v.name = newName}
});

Answer 2

Use Array#forEach over Array#filter

Note that == or === should be used to compare, = will assign the value!

Array#forEach with condition should be enough just to update existing array of object.

var arrayOfObjects = [{
  id: 1,
  name: 'Alpha'
}, {
  id: 2,
  name: 'Bravo'
}];

var setNameById = function(id, newName) {
  var filtered = arrayOfObjects.filter(function(obj) {
    return obj.id == id;
  });
  filtered.forEach(function(el) {
    el.name = newName;
  });
  return filtered;
};

console.log(JSON.stringify(arrayOfObjects));
var filtered = setNameById(2, 'Charlie');
console.log(JSON.stringify(filtered));

Or use Array#map

var arrayOfObjects = [{
  id: 1,
  name: 'Alpha'
}, {
  id: 2,
  name: 'Bravo'
}];

var setNameById = function(id, newName) {
  return arrayOfObjects.filter(function(obj) {
    return obj.id == id;
  }).map(function(el) {
    el.name = newName;
    return el;
  });
};

console.log(JSON.stringify(arrayOfObjects));
var filtered = setNameById(2, 'Charlie');
console.log(JSON.stringify(filtered));

Answer 3

Filter returns an array. So will have to use index in your approach.

Your Approach

var arrayOfObjects = [{
  id: 1,
  name: 'Alpha'
}, {
  id: 2,
  name: 'Bravo'
}];

var setNameById = function(id, newName) {
  arrayOfObjects.filter(function(obj) {
    return obj.id = id;
  })[0].name = newName;
};

console.log(JSON.stringify(arrayOfObjects)); // initial array logged
setNameById(2, 'Charlie');
console.log(JSON.stringify(arrayOfObjects));

array.find

If you are sure it will return only one value, use array.find

var arrayOfObjects = [{
  id: 1,
  name: 'Alpha'
}, {
  id: 2,
  name: 'Bravo'
}];

var setNameById = function(id, newName) {
  arrayOfObjects.find(function(obj) {
    return obj.id = id;
  }).name = newName;
};

console.log(JSON.stringify(arrayOfObjects)); // initial array logged
setNameById(2, 'Charlie');
console.log(JSON.stringify(arrayOfObjects));

array.forEach

If there can be more than 1 object with same search key (id in this case), use array.forEach instead of array.filter and then loop over filtered array

var arrayOfObjects = [{
  id: 1,
  name: 'Alpha'
}, {
  id: 2,
  name: 'Bravo'
}];

var setNameById = function(id, newName) {
  arrayOfObjects.forEach(function(obj) {
    if(obj.id = id) obj.name = newName;
  });
};

console.log(JSON.stringify(arrayOfObjects)); // initial array logged
setNameById(2, 'Charlie');
console.log(JSON.stringify(arrayOfObjects));