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Rediscovering JavaScript: ES6, ES7 & ES8

Solution Review: Injecting Multiple Properties

Explore how to inject multiple properties into JavaScript objects using the defineProperties method. Understand how to create dynamic getters for integer and fractional parts of numbers, enhancing your metaprogramming skills with practical examples.

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Solution

Let’s start understanding the solution code.

Node.js
'use strict';
Object.defineProperties(Number.prototype, {
  integerPart: {
    get: function() {
      return this.toString().split('.')[0];
    }
  },
  fractionalPart: {
    get: function() { return this.toString().split('.')[1] || 0; }
  }
});                            
const printParts = function(number) {
  return `whole: ${number.integerPart} decimal: ${number.fractionalPart}`;
};
console.log(printParts(22.12));    //whole: 22 decimal: 12
console.log(printParts(.14));      //whole: 0 decimal: 14
console.log(printParts(-23.19));   //whole: -23 decimal: 19
console.log(printParts(42));       //whole: 42 decimal: 0

Explanation

For injection properties, we use a special defineProperties method. The defineProperties() method takes only two parameters:

  1. The candidate object for injection
  2. An object with properties as
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