Is JavaScript dynamically typed language?

Yes, JavaScript is dynamically typed language. In dynamically typed languages, you no need to specify the data type to a variable, type of the variable is determined at run time. Python, JavaScript, Julia are the examples of dynamically typed languages.

HelloWorld.js

var a = "Hello Wolrd";
console.log("Value of a is " + a);

a = 10;
console.log("Value of a is " + a);

a = true;
console.log("Value of a is " + a);

a = undefined;
console.log("Value of a is " + a);

a = {"name": "Krishna"};
console.log("Value of a is " + a);

Output

Value of a is Hello Wolrd
Value of a is 10
Value of a is true
Value of a is undefined
Value of a is [object Object]

As you see above snippet, I defined a variable ‘a’ like below.

var a = "Hello Wolrd";

Later I assigned a to the value 10.

a = 10;

Later I assigned a to true, undefined, and an object {"name": "Krishna"}. This kind of redefinitions are possible in dynamically typed languages, but not on statically typed languages.

Type conversion

If an expression involves a string and number value with + operator, then JavaScript converts the number values to strings.

var x = "Hello" + 5;  //Hello5

console.log(x)

If the expression contains other operators (other than +), then number values are not converted to strings.

HelloWorld.js

var x = "Hello" - 5;  //NaN
var y = "55"-5; //50
var z = "55"+5; //555

console.log(x);
console.log(y);
console.log(z);

If you would like to know more differences between static and dynamically typed languages, I would recommend you to go through my below post.

https://self-learning-java-tutorial.blogspot.com/2015/11/statically-vs-dynamically-typed.html

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