Strings and JavaScript

Declare String Variables

When you are defining a string you must start and end with a single or double quote. What happens when you need a literal quote: " or ' inside of your string?

In JavaScript, you can escape a quote from considering it as an end of string quote by placing a backslash (\) in front of the quote.

var sampleStr = "Alan said, \"Peter is learning JavaScript\".";

This signals to JavaScript that the following quote is not the end of the string, but should instead appear inside the string. So if you were to print this to the console, you would get:

Alan said, "Peter is learning JavaScript".

Concatenating Strings with Plus Operator

Concatenating adds two Stings together...

In JavaScript, when the + operator is used with a String value, it is called the concatenation operator. You can build a new string out of other strings by concatenating them together.


'My name is Alan,' + ' I concatenate.'

Concatenating Strings with the Plus Equals Operator

We can also use the += operator to concatenate a string onto the end of an existing string variable. This can be very helpful to break a long string over several lines.

Watch out for spaces. Concatenation does not add spaces between concatenated strings, so you'll need to add them yourself.

Constructing Strings with Variables

Sometimes you will need to build a string, Mad Libs style. By using the concatenation operator (+), you can insert one or more variables into a string you're building.

var ourName = "Free Code Camp";
var ourStr = "Hello, our name is " + ourName + ", how are you?";

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var myName = "Margot the Magnificient ";
var myStr = "My name is " + myName + "and I am swell!";
Just as we can build a string over multiple lines out of string literals, we can also append variables to a string using the plus equals (+=) operator.

var anAdjective = "awesome!";
var ourStr = "Free Code Camp is ";
ourStr += anAdjective;

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var someAdjective = "fucking crazy man!";
var myStr = "Learning to code is ";
myStr += someAdjective;

Find the Length of a String

You can find the length of a String value by writing .length after the string variable or string literal.

"Alan Peter".length; 10

For example, if we created a variable var firstName = "Charles", we could find out how long the string "Charles" is by using the firstName.length property.

Use Bracket Notation to Find the First Character in a String

Bracket notation is a way to get a character at a specific index within a string.

Most modern programming languages, like JavaScript, don't start counting at 1 like humans do. They start at 0. This is referred to as Zero-based indexing.

For example, the character at index 0 in the word "Charles" is "C". So if var firstName = "Charles", you can get the value of the first letter of the string by using firstName[0].

Understand String Immutability

In JavaScript, String values are immutable, which means that they cannot be altered once created.

For example, the following code:

var myStr = "Bob";
myStr[0] = "J";
cannot change the value of myStr to "Job", because the contents of myStr cannot be altered. Note that this does not mean that myStr cannot be changed, just that the individual characters of a string literal cannot be changed. The only way to change myStr would be to assign it with a new string, like this:

var myStr = "Bob";
myStr = "Job";

Use Bracket Notation to Find the Nth Character in a String

You can also use bracket notation to get the character at other positions within a string.

Remember that computers start counting at 0, so the first character is actually the zeroth character.

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