Primitives
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Briefly describe the history of JavaScript and its purpose as a language
Define JavaScript variables and data structures
Utilize primitives and operators in order to solve problems using JavaScript
Manipulate integers, floating point, and decimal numbers
Manipulate strings
Use booleans as return values, as variables, and in the context of a conditional
Then
developed by Brendan Eich (for Netscape, now Mozilla)
10 days
went through a few different names before settling on JavaScript (Java was popular)
taken to for standardization
Now
JavaScript is THE front-end language
clunky, , but it works and is web-driven!
tons of open source libraries
also used as a backend language, using Node.js
working on
Comments come in two forms
Numbers are one of the types of values we want to be able to interact and play with in JS.
In JS these are both the same type of object, which it calls Numbers.
This can infrequently cause problems!
How would you get the 2 + 2
to execute before the * 3
? In other words, how would you change this expression to get 12?
Strings are collections of letters and symbols known as Characters, and we use them to deal with words and text in Javascript. Strings are just another type of value in Javascript.
You can use operators on strings too! Try typing "John" + "Jane"
. This is called String concatenation
Try this...
Without removing the quotes, how would you get this to equal 2?
Booleans are a type that can only have one of two values: true or false.
Javascript can be a little cheap with the number of operations it allows you to do. For example, how is someone supposed to square a number or cube a number easily? Luckily there is a special Math
object with some very useful methods.
Taking a number to some power
? Then just use Math.pow
Taking a square root
Need a random
number? Then use Math.random
.
Since Numbers can be Floats or Integers we often want to get rid of remaining decimal places, which can be done using Math.floor
.
Having made some expressions it becomes evident we want to store these values.
The main note to make here is that these variables should always have the let
keyword and use camelCase
. You also may see the var
keyword as well from time to time. We will talk more about the difference later.
In Javascript we just discussed two types of values we can use. We call these values objects, which for now just means that in addition to storing some data you also get to use some helpful methods when you are working with them.
In JavaScript, almost everything is an object (primitive types are the exception).
If you want to turn a number into a string you can use a helpful method called toString
.
Numbers
.toString()
- converts a number to a string
.toFixed()
, - converts a number to a fixed string representation
parseInt('33')
- converts a string to an integer
parseFloat('3.1')
- converts a string to a floating point number
Strings
.split('')
- converts a string into an array split in a provided character
.indexOf('s')
- returns the index of the first appearance of a provided string
.toUpperCase()
- converts a string to all caps
.toLowerCase()
- converts a string to all lowercase
.replace('old', 'new')
- replaces the first appearance of a string with a new string
Note that most of these functions are called on an object, while functions like parseInt()
and parseFloat()
only take in arguments.
[Type coercion is the process of converting value from one type to another]().)
More info: