JS: Javascript
with nothing to do with Java, Java is the original fire, which is to rub the door Java heat, so named Javascript
Notes:
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Entry Mode
Mode 1: directly in the script internal write js code
embodiment 2: using the src attribute of the script tag is introduced into an external js code files
declare variables:
var name = 'Hello'
the let name = 'Hello'
js variable naming:
alphanumerical underscores $
numbers can not start and can not be present keyword conflicts
python are recommended: USER_NAME
Javascript recommended (hump body): the userName, UserName
Js data type
value type
string type
Boolean
undefined
objects
null
array [1,2,3,4]
customized object { "name" : "Jason"}
Symbol
the JSON objects
the stringify
the parse
js defined two ways of regular
REG1 = new new the RegExp ( '^ [A-Za-Z] [A-Za-Z0-9] {5,9} $')
REG2 = / ^ [A-Za-Z] [a-Za-z0-9] { 5,9} $ /
pit highlights:
1. regular expressions do not write spaces
2. global mode lastindex match
when matching 3 does not pass any parameters to match the default undefined
BOM
Object Model broswer
the DOM (******)
the Document Object Model
direct lookup (******)
the above mentioned id
class (class)
tag (label)
indirect Find