Intro to JavaScript II

Strings

Strings in JavaScript allow us to store a series of characters within double quotes " or single quotes '.

If you choose double or single quotes, continue using one or the other for consistency in your code.

We will mostly be using single quotes ' ourselves.

Type the following into your console and hit Enter after each line

'This is a string!'

'You type any characters you want in here'

'You can even do something called Concatenation! Let´s talk about that.'

In addition to being used for mathematical operations on numbers, the + operator can can be used to concatenate — that is, to combine — strings together.

By using + when typing a string, we can combine our string with other strings or other types like numbers. This is called concatenation.

Run the following code in your console

'I can take a string ' + 'and another string ' + 'and combine it with a third!'

When we hit enter the strings are concatenated (combined) and the expression evaluates to a single string.

We add a space to the end of each string so that it reads normally. Run the following code to see this in action:

'I can take a string' + 'and another string' + 'and combine it with a third!'

Although the above code works and they need to be familiar with it, there is a newer way of doing this that is generally preferred, but we need to learn about variables first to understand that way.

Why might we want to concatenate strings?

We might want to do that for things like: The user inputs their name and we want to combine it with the string 'Welcome ' to say something like 'Welcome Diane', etc.

Booleans

A boolean is a data type representing one of two values: true or false.

Type the following into the console, pressing Enter after each line:

1 === 1;

1 === '1';

'hi' === 'hi';

1 === 2;

'hi' === 'hello';

These expressions evaluate to a boolean value, which is to say that they evaluate to true or false.

We use three equals signs === to mean "is equal to".

Line 1 is evaluating whether 1 "is equal to" 1, etc.

Why does 1 === '1' evaluate to false?

That is because 1 is a number and '1' is a string, so even though they have the same value, they have different types. To evaluate to true the things being compared with === must be equal in value and type.

In JavaScript there are a few ways to compare elements, for now we will stick with === but feel free to do your own research on the topic.