Strings (Text)

A lot of this applies to other languages but the syntax may be slightly different.

Strings and Chars

Every letter or punctuation mark typed from the keyboard is called a character. Many characters together create a string of text. For Example: The word hello is a string made of the characters 'h' 'e' 'l' 'l' 'o'.

"This is a string" | 'This is a string' | `This is a string`

Strings are a special type of variable called an object. Similar to a pencil, objects in code have properties (colour, length, weight) and methods (write, erase). A string is a bunch of chars put together (like a on a string, get it?) and has a length as well as some methods. Another term for this special object is an Array. For Example: the separate characters 'h' 'e' 'l' 'l' 'o' can be strung together to make "hello".

We will have an entire lesson on arrays but what you need to know is that you can access each individual letter (character) in a string because they each have an index (like a home address) starting at zero.

let someString = "Sample string FTW!";
console.log(someString[0]); // Prints 'S'
console.log(someString[5]); // Prints 'e'
console.log(someString.length); // Prints the length - 18

Special Characters

New lines, quotes, and tabs are all examples of text that needs to be escaped. You need to use the slash character (\) to tell the interpreter that there is a special circumstance.

Escape Sequence

Name

Symbol

\b

backspace

<BS>

\t

horizontal tab

<HT>

\n

line feed (new line)

<LF>

\v

vertical tab

<VT>

\f

form feed

<FF>

\r

carriage return

<CR>

\"

double quote

"

\'

single quote

'

\\

backslash

\

The above table was shamefully borrowed from http://es5.github.io/x7.html#x7.8.4 (table 4)

Use escape sequences to print special characters

Example

let myOutput = "This is a single line but\nthis is a completely new line";
console.log(myOutput);
console.log("I used \"\\n\" to create the new line");
/* Output:
This is a single line but
this is a completely new line
I used "\n" to create the new line
*/

Concatenation

The + operator performs string concatenation (add one string to the end of another) as long as one of the items is already a string. This means it combines letters together: 'ab' + 'c' = 'abc'

Example:

let myString = "She sold ";
console.log(myString + 17 + " sea shells.");
// Output: She sold 17 sea shells.

You can also use += like this:

var greeting = "Hello";
var world = " World!";
greeting += world;
// This sets the value of myString to "Hello World!"

The above is an abbreviation for greeting = greeting + world;

Template Literals

Template literals take a bit of getting used to but they are a great way to work with Strings in JS. First of all, you don't need to worry about escaping the " or ' characters. You don't need \n for a new line if you simply put your string one multiple lines. Finally, you can get away from using the + symbol for concatenation and insert your variables into the string using ${variable}. It makes for more readable code, which is important. Example:

Examples

Basic String Work

Built-in Functions

Strings in Javascript, Java, and Python have a bunch of special functions that you can use to search or replace text. Let's take the string "Goodbye Sunshine!" and examine what we can do in Javascript (feel free to play around):

Play around with strings. Get used to their methods and functionalities.

Important Note

Aside from .length (which is a property of the string), you can manipulate or do many things with some pretty awesome built-in functions. It is worth researching these functions in order to program efficiently. However, there will be many assignments in our course where you will not be permitted to use the built-in functions. This is to force you to think like a programmer - remember, this is an introductory course.

The assignments will state, in the description, what is permitted.