Equivalent of angular.equals in angular2

Question

I am working on migration of angular 1 project to angular 2 . In angular 1 project I was using angular.equals for object comparison angular.equals($ctrl.obj1, $ctrl.newObj); , I searched online for equivalent method in angular 2 but could not find any matching result.

Solution 1

@Günter Yes you are right there is no equivalent in angular2 . While searching more I found third party library lodash which will do same job as angular.equals and syntax is same as angular one and this library solves my problem

Code example from lodash documentation

var object = { 'a': 1 };
var other = { 'a': 1 };
 
_.isEqual(object, other);
// => true
 
object === other;
// => false

Solution 2

I rewrote Ariels answer (thank you!) to be TSLINT-friendly. You can also save some continues by using else if, but I think this is more clear. Maybe someone else needs it too:

export function deepEquals(x, y) {
  if (x === y) {
    return true; // if both x and y are null or undefined and exactly the same
  } else if (!(x instanceof Object) || !(y instanceof Object)) {
    return false; // if they are not strictly equal, they both need to be Objects
  } else if (x.constructor !== y.constructor) {
    // they must have the exact same prototype chain, the closest we can do is
    // test their constructor.
    return false;
  } else {
    for (const p in x) {
      if (!x.hasOwnProperty(p)) {
        continue; // other properties were tested using x.constructor === y.constructor
      }
      if (!y.hasOwnProperty(p)) {
        return false; // allows to compare x[ p ] and y[ p ] when set to undefined
      }
      if (x[p] === y[p]) {
        continue; // if they have the same strict value or identity then they are equal
      }
      if (typeof (x[p]) !== 'object') {
        return false; // Numbers, Strings, Functions, Booleans must be strictly equal
      }
      if (!deepEquals(x[p], y[p])) {
        return false;
      }
    }
    for (const p in y) {
      if (y.hasOwnProperty(p) && !x.hasOwnProperty(p)) {
        return false;
      }
    }
    return true;
  }
}

Solution 3

Instead of writing a function to iterate through the objects, you could just use JSON.stringify and compare the two strings?

Example:

var obj1 = {
  title: 'title1',
  tags: []
}

var obj2 = {
  title: 'title1',
  tags: ['r']
}


console.log(JSON.stringify(obj1));
console.log(JSON.stringify(obj2));


console.log(JSON.stringify(obj1) === JSON.stringify(obj2));

Solution 4

In Angular 2 you should use pure JavaScript/TypeScript for that so you can add this method to some service

private static equals(x, y) {
    if (x === y)
        return true;
    // if both x and y are null or undefined and exactly the same
    if (!(x instanceof Object) || !(y instanceof Object))
        return false;
    // if they are not strictly equal, they both need to be Objects
    if (x.constructor !== y.constructor)
        return false;
    // they must have the exact same prototype chain, the closest we can do is
    // test there constructor.

    let p;
    for (p in x) {
        if (!x.hasOwnProperty(p))
            continue;
        // other properties were tested using x.constructor === y.constructor
        if (!y.hasOwnProperty(p))
            return false;
        // allows to compare x[ p ] and y[ p ] when set to undefined
        if (x[p] === y[p])
            continue;
        // if they have the same strict value or identity then they are equal
        if (typeof (x[p]) !== "object")
            return false;
        // Numbers, Strings, Functions, Booleans must be strictly equal
        if (!RXBox.equals(x[p], y[p]))
            return false;
    }
    for (p in y) {
        if (y.hasOwnProperty(p) && !x.hasOwnProperty(p))
            return false;
    }
    return true;
}

Solution 5

a = { name: 'me' }
b = { name: 'me' }
a == b // false
a === b // false
JSON.stringify(a) == JSON.stringify(b) // true
JSON.stringify(a) === JSON.stringify(b) // true

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