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

Compare Objects for Equivalent Properties

Write a JavaScript program to compare two objects to determine if the first 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
// Define a function called `matches` that takes two objects as arguments and checks if the first object contains all the key-value pairs of the second object.
const matches = (obj, source) =>
  // Iterate over each key in the source object and check if it exists in the obj object and has the same value.
  Object.keys(source).every(key => obj.hasOwnProperty(key) && obj[key] === source[key]);
// Test cases:
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

Output:

true
false
false

Flowchart:

Live Demo:

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

For more Practice: Solve these Related Problems:

• Write a JavaScript program that deeply compares two objects, including nested properties, and returns true if they are equivalent.
• Write a JavaScript function that checks if all property values in one object are contained in another, ignoring extra properties.
• Write a JavaScript program that compares two objects for equivalent property values but ignores properties with undefined values.

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