Best method for constructing an object from an array of objects

Question

Best method for constructing an object from an array of objects

Currently, I am in the process of constructing an object from a collection of objects using the following code snippet:

var popOverOptions = {
  defaultOption: true
}

if (a) {
  options.push({a: "b"});
}

if (c) {
  options.push({c: "d"});
}

// Iterating through array of objects
for (var i = 0; i < options.length; i++) {
   // Merging objects in array with popoverOptions object
   for (key in options[i]) {
     popoverOptions[key] = options[i][key]
   }
}

I'm exploring possible optimizations for this code and wondering if there are more efficient ways to achieve the same result, perhaps utilizing .reduce(), .forEach(), or another method.

javascript arrays object

Answer 1

Answer №1

Utilizing ECMAScript 6 features, you have two options:

Object.assign can be used to copy properties into popOverOptions
The spread operator allows for expanding the options array.

Object.assign(popOverOptions, ...options);

Answer 2

Utilizing ECMAScript 6 features, you have two options:

Object.assign can be used to copy properties into popOverOptions
The spread operator allows for expanding the options array.

Object.assign(popOverOptions, ...options);

Answer 3

Answer №2

To improve the efficiency of the loop, consider optimizing it in the following way:

for (var i=0, n=options.length; i<n; ++i) {

This method reduces the frequency of accessing options.length, which can be slower compared to using a local variable.

Another small optimization technique involves:

for (var i=options.length-1; i--; /* empty */) {

Reference:

Answer 4

To improve the efficiency of the loop, consider optimizing it in the following way:

for (var i=0, n=options.length; i<n; ++i) {

This method reduces the frequency of accessing options.length, which can be slower compared to using a local variable.

Another small optimization technique involves:

for (var i=options.length-1; i--; /* empty */) {

Reference:

Answer 5

Answer №3

To improve performance, it is recommended to cache the length of an array.

If all keys in the array elements are identical, you can achieve a significant speed boost (especially in Chrome) by caching Object.keys(options[0]) and iterating through them.

Even if the keys are not the same for each element, you can still experience around a 25% increase in speed by iterating through Object.keys(options[i]).

var options= [];

for(var i = 0 ; i <= 1000 ; i++) {  //create array of objects with random numbers
  options[i]= {};
  for(var j = 0 ; j <= 5000 ; j++) {
    options[i][j]= Math.random();
  }
}

var popOverOptions = {};

function keyin() {
  var timer= new Date();
  for(var i = 0, leni = options.length ; i < leni; i++) {
    for(var key in options[i]) {
      popOverOptions[key] = options[i][key];
    }
  }
  alert((new Date()-timer)/1000+' seconds');
} //keyin

function objkeys(same) {
  var timer= new Date(),
      keys= Object.keys(options[0]);

  for(var i = 0, leni = options.length ; i < leni; i++) {
    if(!same) keys= Object.keys(options[i]);
    for(var key = 0, lenk = keys.length ; key < lenk ; key++) {
      popOverOptions[keys[key]] = options[i][keys[key]];
    }
  }
  alert((new Date()-timer)/1000+' seconds');
} //objkeys

<button onclick="keyin()">key in options</button><br>
<button onclick="objkeys(true)">Object.keys, same keys per element</button><br>
<button onclick="objkeys(false)">Object.keys, different keys per element</button>

Answer 6

To improve performance, it is recommended to cache the length of an array.

If all keys in the array elements are identical, you can achieve a significant speed boost (especially in Chrome) by caching Object.keys(options[0]) and iterating through them.

Even if the keys are not the same for each element, you can still experience around a 25% increase in speed by iterating through Object.keys(options[i]).

var options= [];

for(var i = 0 ; i <= 1000 ; i++) {  //create array of objects with random numbers
  options[i]= {};
  for(var j = 0 ; j <= 5000 ; j++) {
    options[i][j]= Math.random();
  }
}

var popOverOptions = {};

function keyin() {
  var timer= new Date();
  for(var i = 0, leni = options.length ; i < leni; i++) {
    for(var key in options[i]) {
      popOverOptions[key] = options[i][key];
    }
  }
  alert((new Date()-timer)/1000+' seconds');
} //keyin

function objkeys(same) {
  var timer= new Date(),
      keys= Object.keys(options[0]);

  for(var i = 0, leni = options.length ; i < leni; i++) {
    if(!same) keys= Object.keys(options[i]);
    for(var key = 0, lenk = keys.length ; key < lenk ; key++) {
      popOverOptions[keys[key]] = options[i][keys[key]];
    }
  }
  alert((new Date()-timer)/1000+' seconds');
} //objkeys

<button onclick="keyin()">key in options</button><br>
<button onclick="objkeys(true)">Object.keys, same keys per element</button><br>
<button onclick="objkeys(false)">Object.keys, different keys per element</button>

Best method for constructing an object from an array of objects

Answer №1

Answer №2

Answer №3

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