How to write JavaScript: A crash course

- [Instructor] Before we start writing JavaScript,…we need to know the basic rules of the language.…Some of these are hard rules…that define how the language itself works,…others are conventions that decide how we write JavaScript,…so it's easier to read for ourselves, and for others.…Rule number one JavaScript is case sensitive.…This means when you use your shift or capslock keys,…it really matters.…Unlike in HTML and CSS, where you can use upper…and lower case letters willy-nilly,…in JavaScript the casing of a word matters.…

If, for example, you create a variable named greenDuck,…with a capitalized D, and then try to reference it…with a lowercase d,…JavaScript sees them as two completely different things…and you get an error.…This case sensitivity matters everywhere…except inside quoted strings of texts.…For example, you may have noticed…when we got the date from the browser,…we typed out var date equals new date with a capitalized D,…well, if you try to do the same with a lowercase d,…you get an error.…

That's because new date with a capitalized D,…