Node.js by Example: Variables

In JavaScript, variables are explicitly declared and used to store the information you need.

var declares 1 or more variables.

 
var a = "initial"
console.log(a)

You can declare multiple variables at once.

 
var b = 2, c = 1;
console.log(b, c)

JavaScript has no type and variables can be reassigned to different types.

 
var d = true;
console.log(d);
d = "apple";
console.log(d);

Variables declared without a corresponding initialization are undefined.

 
var e;
console.log(e);

let is similar to var but block scoped instead of function scoped.

 
let foo = 1;
{
    let foo = 2;
    console.log(foo);
}
console.log(foo);

Modern JavaScript linters will protect against the use of var to prefer block scoped let.

 
$ node variables.js
initial
2 1
true
apple
undefined
2
1

Next example: .

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