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Overview

• a string is an immutable value with 16 ordered bits, each of which represents a Unicode character.
• the length of a string is the number of 16-bit values it contains.
• some Unicode characters whose codepoints do not fit in 16 bits are encoded following the rules of UTF-16 as a sequence of two 16-bit values.

var p = "π";    //π is 1 character with 16-bit codepoint 0x03c0
var e = "e"    //e is 1 character with 17-bit codepoint 0x1d452
p.length    // => 1
e.length     // => 2

• we can use \n to include a newline character, \ to break a string literal across multiple lines.

"two\nlines"    //there are 2 lines
"one\        //there is only 1 line.
line\        
only"

• when combining JavaScript and HTML, it is a good idea to use one style of quotes for JavaScript, and the other style of HTML.

<button onclick="alert('Aloha')">Click me</button>

Escape Sequence(轉義字符)

Pattern Matching

• create objects that reptresent textual patterns with RegExp().

var text = "testing: 1, 2, 3";
var pattern = /\d+/g
pattern.test(text)    // => true
text.search(pattern)    // => 9: position of first match
text.match(pattern)    // => [ "1", "2", "3"]: array of all matches
text.replace(pattern, "#")    // => "testing: #, #, #"
text.split(/\D+/);    // => [ "", "1", "2", "3"]: split on non-digits