Variable mutation and type coercion in Javascript

Variable mutation and type coercion in Javascript

In this chapter, you will learn about Variable mutation and type coercion in Javascript. Let’s consider the below code snippet,

let actor = 'John';
let actroBirthYear = 1973;
let isProducer = true;
let nationality = 'American';

console.log('The'+' '+actor+' '+'is an'+' '+nationality+' '+'actor, And birth year is :'+actroBirthYear+', Is producer :'+' '+isProducer);

// // output
// // The John is an American actor, And birth year is :1973, Is producer : true

As we can see the output in console of the above code snippet, the output is a complete string and the understand the type variables which we used in the code snippet

1. The Variable actor type is: String
2. The Variable actorAge type is: Number
3. The Variable isProducer type is: Boolean
4. The Variable nationality type is: String

Even when the Variable actorAge is a Boolean and isProducer is Boolean, the Javascript is writing the string into the console. Here all kind of Variables been converted to the string. This works with the help of type coercion in Javascript.

What is type coercion in Javascript?
The process that Javascript automatically converts types of Variables to another type when it is needed.

What is a variable mutation in Javascript?
Javascript allows changing the value of a variable anywhere in the program. We can define the multiple variables in the same line and values can be assigned later. The Values of the Variables can be redefined. Let’s see the below code snippet

Variable mutation: Variable mutation in Javascript allows to change the value of a variable.

let actor, actroBirthYear, isProducer, nationality;

console.log(actor);
console.log(actroBirthYear);
console.log(isProducer);
console.log(nationality);

// output
// undefined
// undefined
// undefined
// undefined

actor = 'John'; 
actroBirthYear = 1990;
isProducer = true; 
nationality = 'Indian';

console.log(actor);
console.log(actroBirthYear);
console.log(isProducer);
console.log(nationality);

// output
// John
// 1990
// true
// Indian

actor = 'Mickel'; 
actroBirthYear = 1995;
isProducer = false; 
nationality = 'UK';

console.log(actor);
console.log(actroBirthYear);
console.log(isProducer);
console.log(nationality);

// output
// Mickel
// 1995
// false
// UK

As you can see in the above code snippet, the 4 variables actor, actroBirthYear, isProducer, nationality is been declared in the same line. Later we assigned the value as

actor = 'John'; 
actroBirthYear = 1990;
isProducer = true; 
nationality = 'Indian';

And later we assigned a new value

actor = 'Mickel';
actroBirthYear = 1995;
isProducer = false;
nationality = 'UK';