Learn Javascript Object Methods with examples

Objects in JavaScript are collections of key/value pairs. The values can consist of properties and methods and may contain all other JavaScript data types, such as strings, numbers, and Booleans.


The toString() method takes no arguments; it returns a string that somehow represents the value of the object on which it is invoked.

JavaScript invokes this method of an object whenever it needs to convert the object to a string. This occurs, for example, when you use the + operator to concatenate a string with an object or when you pass an object to a method that expects a string.

let point = {
x: 1,
y: 2,
toString: function() { return `(${this.x}, ${this.y})`; }


// Output : (1, 2)         


The JavaScript Number toLocaleString() method returns a string with a language-sensitive representation of this number. The purpose of this method is to return a localized string representation of the object. The default toLocaleString() method defined by Object doesn’t do any localization itself: it simply calls toString() and returns that value.

let number = 500000;
console.log(number.toLocaleString());   //  Output : 500,000

let number1 = 875643.789;
console.log(number1.toLocaleString("en-IN"));  //  Output : 8,75,643.789

let currency = number1.toLocaleString("de-DE", {
  style: "currency",
  currency: "EUR",
  maximumSignificantDigits: 6,

console.log(currency);   // Output : 875.644 €           


The valueOf() method is much like the toString() method, but it is called when JavaScript needs to convert an object to some primitive type other than a string—typically, a number. JavaScript calls this method automatically if an object is used in a context where a primitive value is required.

let point = {
x: 4,
y: 5,
valueOf: function() { return Math.hypot(this.x, this.y);


// Output : 6.4031242374328485            


In JavaScript, the JSON.stringify() function looks for functions named toJSON in the object being serialized. If an object has a toJSON function, JSON.stringify() calls toJSON() and serializes the return value from toJSON() instead.

x = {a:5, b:{c:[false,null,""]}}; // Define a test object
y = JSON.stringify(x);            
z = JSON.parse(y); 

// Output : {"a":5,"b":{"c":[false,null,""]}}             
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Ankit Patel

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