JavaScript (ii) Basic concepts

JS Case-sensitive

　　Label selectors are case-insensitive in HTML/CSS

　　ID class selector is case sensitive

where property Name Property Name property value is not case sensitive

　　the case-insensitive content part of the inline event onclick, etc.

More than one of the same inline events will be flushed out of the back

identifiers (variables, functions, names of properties)

Naming method: The first character must be a letter , an underscore , or a

Comment Method

　　Single-line comment//

Paragraph comment/* * *

Strict mode

"Use strict"//Add to first line

Statement

ECMAScript in the statement; End

　　If you do not end with a semicolon, the compiler automatically resolves to see if the following code can be executed with him if possible merge if not, add a semicolon after this line

　　Return break automatically add a semicolon regardless of whether it can be executed with the following line

Continue to be executed after the change of line

+ +--on the contrary because he is a unary operator right-associative　　

The variable Ecmascript variable is loosely typed　　

Declaring variable var

VAR declared variable will be in advance var variable cannot be deleted because Var is equivalent to applying for a space

A global variable that is generated without a declaration can be deleted because he is the equivalent of adding a property to the Window object

Because the properties of an object are unordered, there is no need to advance so the variables generated in this way do not advance

Small problem

　　

var a="ABCD",    a.len=4//undefined

Here is the wrapper class only object has method other just wrapper class

JavaScript (ii) Basic concepts