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JavaScript: Compare two objects to determine if the first one contains equivalent property values to the second one

JavaScript fundamental (ES6 Syntax): Exercise-1 with Solution

Write a JavaScript program to compare two objects to determine if the first one contains equivalent property values to the second one.

  • Use Object.keys() to get all the keys of the second object.
  • Use Array.prototype.every(), Object.prototype.hasOwnProperty() and strict comparison to determine if all keys exist in the first object and have the same values.

Sample Solution:

JavaScript Code:

//#Source https://bit.ly/2neWfJ2
const matches = (obj, source) =>
  Object.keys(source).every(key => obj.hasOwnProperty(key) && obj[key] === source[key]);
console.log(matches({ age: 25, hair: 'long', beard: true }, { hair: 'long', beard: true })); // true
console.log(matches({ hair: 'long', beard: true }, { age: 25, hair: 'long', beard: true })); // false
console.log(matches({ hair: 'long', beard: true }, { age: 26, hair: 'long', beard: true })); // false

Sample Output:

true
false
false

Flowchart:

flowchart: Compare two objects to determine if the first one contains equivalent property values to the second one

Live Demo:

See the Pen javascript-basic-exercise-1-1 by w3resource (@w3resource) on CodePen.


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JavaScript: Tips of the Day

How to remove a specific item from an array?

Find the index of the array element you want to remove using indexOf, and then remove that index with splice.

The splice() method changes the contents of an array by removing existing elements and/or adding new elements.

const array = [2, 5, 9];

console.log(array);

const index = array.indexOf(5);
if (index > -1) {
  array.splice(index, 1);
}

// array = [2, 9]
console.log(array);

The second parameter of splice is the number of elements to remove. Note that splice modifies the array in place and returns a new array containing the elements that have been removed.

For the reason of completeness, here are functions. The first function removes only a single occurrence (i.e. removing the first match of 5 from [2,5,9,1,5,8,5]), while the second function removes all occurrences:

function removeItemOnce(arr, value) {
  var index = arr.indexOf(value);
  if (index > -1) {
    arr.splice(index, 1);
  }
  return arr;
}

function removeItemAll(arr, value) {
  var i = 0;
  while (i < arr.length) {
    if (arr[i] === value) {
      arr.splice(i, 1);
    } else {
      ++i;
    }
  }
  return arr;
}
//Usage
console.log(removeItemOnce([2,5,9,1,5,8,5], 5))
console.log(removeItemAll([2,5,9,1,5,8,5], 5))

Ref: https://bit.ly/2N9nKRp