Why am I able to run and build Javascript without semicolons?

Question

In an online course, I'm following on Udemy, the instructor is putting semicolons after lines and says they are needed. I forgot to put some because I'm just getting off of Python and the code still ran.

var firstName = 'John';
console.log(firstName);

var lastName = 'Smith';
var age = 28;

console.log(lastName)
console.log(age)

When I right click on the browser and click on console the first, last name and age are displayed. Can anyone help explain why its working without the semicolons? I'm assuming they are needed when writing Javascript.

score 1 · Answer 1 · answered Nov 11 '19 at 06:05

1

JavaScript doesn't actually need semicolons. Unless you're writing more than one statement on the same line (please don't, with the exception of for loops)

answered Nov 11 '19 at 06:05

shiruken

25
4

Why are for loops exceptions? – mplungjan Nov 11 '19 at 06:11

score 1 · Accepted Answer · edited Nov 11 '19 at 06:08

This is because Javascript parser will automatically insert semicolon for you in the following situations:

Copypasta from Flavio Copes' Let’s talk about semicolons in JavaScript

when the next line starts with code that breaks the current one (code can spawn on multiple lines)
when the next line starts with a }, closing the current block
when the end of the source code file is reached
when there is a return statement on its own line
when there is a break statement on its own line
when there is a throw statement on its own line
when there is a continue statement on its own line

For best practices, semicolons should be manually inserted.

Please read this: https://stackoverflow.blog/2009/06/25/attribution-required/ — mplungjan, Nov 11 '19 at 06:10

Why am I able to run and build Javascript without semicolons?

2 Answers2