Basic Functions

Overview

isFinite()

Returns false if the argument is NaN, positive infinity or negative infinity.

isFinite(testValue)

isNaN()

Returns true if the argument, when coerced to a numeric value, is an IEEE-754 'Not A Number' value.

isNaN(testValue)

Note: Using isaNum(x), which is the inverse of isNaN(x) and is used to avoid the confusion of double-negatives. Note: Using isaNum(x), which is the inverse of isNaN(x) and is used to avoid the confusion of double-negatives.

parseInt()

Parses a string up to the first non-digit character (whereas the Number() function parses the entire string as a number).

See What's the difference between parseInt and Number?

parseInt(string, radix)

parseFloat()

Parses a string up to the first non-digit character (whereas the Number() function parses the entire string as a float).

parseInt(string, radix)

encodeURI()

Encodes the entire URI, preserving special chars required for GET and POST requests (e.g., "&" and "="). To encode user entered data, that could contain these chars, use encodeURIComponent() on each component of user data making up the URI.

encodeURI(uri)

encodeURIComponent()

Encodes user data, used as a component of a URI.

encodeURIComponent(userStr)

decodeURIComponent()

decodeURIComponent(encodedUserData)