JavaScript valueOf vs. toString Methods (original) (raw)
Summary: in this tutorial, you will learn the differences between the valueOf() and toString() methods of object in JavaScript.
The object has two similar methods:
valueOf()method returns a primitive value of an object.toString()method return the string representation of an object.
Note that a string is also a primitive value in JavaScript.
The valueOf() and toString() methods serve different purposes. The valueOf() is usually called internally by JavaScript to convert an object to a primitive value.
For example, if you call the valueOf() method on some built-in object like Date, it’ll return a timestamp:
let d = new Date('2024-01-01 12:45:30'); console.log(d.valueOf());Code language: JavaScript (javascript)
Output:
1704087930000Code language: JavaScript (javascript)
In this example, the valueOf() returns a timestamp that represents the Date object.
The toString() method will return a string that represents the Date object:
let d = new Date('2024-01-01 12:45:30'); console.log(d.toString());Code language: JavaScript (javascript)
Output:
Mon Jan 01 2024 12:45:30 GMT+0700 (Indochina Time)Code language: JavaScript (javascript)
For most objects, the valueOf() returns the objects themselves whereas the toString() returns the [object Object].
For example:
`` const person = {
name: 'John Doe',
age: 30,
sayHi: () => {
console.log(Hi);
},
};
console.log(person.valueOf()); console.log(person.toString()); ``Code language: JavaScript (javascript)
Output:
{ name: 'John Doe', age: 30, sayHi: [Function: sayHi] } [object Object]Code language: JavaScript (javascript)
If you don’t want the default return value ([object Object]) of the toString() method, you can override it like this:
`` const person = {
name: 'John Doe',
age: 30,
sayHi: function () {
console.log(Hi);
},
toString: function () {
return {name: "${this.name}", age: ${this.age}};
},
};
console.log(person.toString()); ``Code language: JavaScript (javascript)
Output:
{name: "John Doe", age: 30}Code language: JavaScript (javascript)
Summary
valueOf()method returns a primitive value, called internally by JavaScript, and often used in comparison and mathematical operations.toString()method returns a string representation of an object and often used in string contexts.
Was this tutorial helpful ?