Overview of Strings in JavaScript

 JavaScript provides flexible string objects. String methods allow you to search, convert, and extract information from strings. In JavaScript, strings are made up of zero or more characters enclosed in either double or single quotes.

JavaScript uses Unicode characters, not ASCII. As in C, characters may be equated with integers. For example, if ('a' > 64). Characters may be defined with octal or hex escapes. The less-than and greater-than symbols are represented respectively by \074 and \076 in octal and \x3c and \x3e in hex. (Upper- and lower-case are not considered. \x3c, \X3c and \X3C are equally valid.)

JavaScript provides five special characters for use in strings. Include these characters directly in your strings.

For example, 'This appears on \n two lines'.

Searching strings
indexOf( aString , [aStart]) Searches for a substring, optionally starting at a particular index, e.g., "Hello Dolly".indexOf("ll") returns 2. "Hello Dolly".indexOf("ll", 5) returns 8. If no substring is found, JavaScript returns -1.
lastIndexOf( aString , [aStart]) Searches backwards for a substring, optionally starting at a particular index, e.g., "Hello Dolly".indexOf("ll") returns 8. "Hello Dolly".indexOf("ll", 5) returns 2. If no substring is found, JavaScript returns -1.
Converting strings
parseInt( aString) Returns the integer value of a string. See the Math Overview for an interactive demonstration of parseInt(), e.g., parseInt("8") returns 8. parseInt("8.5") returns 8. parseInt("8Foo") returns 8. parseInt("Foo8") returns NaN (not a number).
parseFloat( aString) Returns the floating-point value of a string. See the Math Overview for an interactive demonstration of parseFloat() and a further description of legal floating-point numbers, e.g., parseFloat("8") returns 8. parseFloat("8.5") returns 8.5. parseFloat("8E2") returns 800. parseFloat("Foo8") returns NaN (not a number).
"" + aNumber Converts a number constant or variable to a string, e.g., ""+8 returns "8". ""+8.5 returns "8.5". ""+myVar returns the string value of the variable myVar.
toLowerCase( aString) Converts a string to lowercase, e.g., "Hello World".toLower() returns "hello world".
toUpperCase( aString) Converts a string to uppercase, e.g., "Hello World".toUpper() returns "HELLO WORLD".
escape( aString) Converts ISO Latin-1 characters to ASCII, e.g., escape("<hello world>") returns "%3CHello%20World%3E".
unescape( aString) Converts ASCII to ISO Latin-1, e.g., unescape("%3CHello%20World%3E") returns "<Hello World>".
Other string operations
charAt( anIndex) Returns the character found at an index. The index starts counting from zero, e.g., "Hello World".charAt(6) returns "W".
substring( aStartIndex, anEndIndex) Returns the characters found between the start and end indices, e.g., "Hello World".substring(0,1) returns "H". "Hello World".substring(4,10) returns "o Worl".
string1 + string2 Creates a new string which appends string1 with string2, e.g., "Hello "+"World" returns "Hello World"
"" + aString Creates a new string which "clones" the original string, e.g., ""+"Hello World" returns a fresh copy of "Hello World".
length() Returns the length of a string, e.g., "Hello World".length returns 11.
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