Examples of mixing numbers and strings:
- “1” + 2 + 4 will evaluate to 124 (looks like if the compiler finds a string the rest will also be considered a string)
- 2 + 5 + “8” will evaluate to 78 (looks like after the compiler finds a string, then it behaves as one, but not before)
- Number(“1”) + 2 + 4 will evaluate to 7
- Instead of Number(), you can use +, like: +”1″ + 2 + 4
Parsing numbers:
- parseInt(“3F”,16); Convert 3F hexadecimal to int. If you use 10 it will be decimal instead
- parseInt will look for numbers at the beginning of the string, as oppose to Number, which will return NAN if a string is assigned to it
- parseFloat parses floats
Other number functions:
- isNaN(x)) Checks if x is a number. Returns true or false accordingly.
- Math.round(number) Rounds the number to its closes integer.
- Math.ceiling(x) Produce the ceiling of a number.
- Math.floor(x) Produce the floor of a number
- Useful function to produce random numbers from 1 to 9: Math.floor(Math.random()*10);
This is a more generic representation of it:
number = Math.floor(Math.random() * total_number_of_choices + first_possible_value)
If you want to select
a number between 2 and 10, then the code would look like this:
var num = Math.floor(Math.random() * 9 + 2);