JavaScript Numbers Flashcards
What are whole numbers in JavaScript called?
Integers
Provide an example of an integer in JavaScript.
5, 0, -100, 9999
What are numbers with decimal points in JavaScript called?
Floating point numbers
Give an example of a floating point number.
3.14, -9.88888, .0000009
How can you represent really large or small numbers in JavaScript?
Using scientific notation
What does ‘9e-6’ represent in decimal form?
.000009
What does ‘9e+6’ represent in decimal form?
9000000
How do you assign a number to a variable in JavaScript?
Using the equals sign (assignment operator)
Provide an example of assigning a number to a variable.
let score = 0; const pi = 3.141592653589793
What happens if you put quotation marks around a number in JavaScript?
It becomes a string, not a number
What is the value stored in the variable aString if defined as const aString = ‘10’;?
A string made up of the character 1 followed by 0
True or False: A number inside quotes is really a number.
False
Fill in the blank: In JavaScript, you can store numbers in _______.
variables
What is a potential issue when treating a string as a number in JavaScript?
It can lead to strange and confusing behavior in math operations
What happens when you try to add two numbers together when the numbers datatypes are both strings instead of a numerical datatype like an int or a float?
It will concatenate the strings, so “10” + “5” will be “105” ( a string) not 15.
How can you use JS to tell what a variable’s datatype is?
Use the typeof operator.
typeof “John” // Returns string
typeof (“John”+”Doe”) // Returns string
typeof 3.14 // Returns number
typeof 33 // Returns number
typeof (33 + 66) // Returns number
typeof true // Returns boolean
typeof false // Returns boolean
typeof 1234n // Returns bigint
typeof Symbol() // Returns symbol
typeof x // Returns undefined
How do you convert a string into an int or float?
parseInt() or parseFloat()
You can also use the unary plus operator, basically just add a + before the var name
+nameOfVarToConvert
