"JavaScript DOM programming art" (second edition) study notes (a)

The book I bought last year but never see, leisure time looked down and found written inside the content is really good, so I decided to take notes while some learning on the blog, so easy to find and watch later.

The best practice is on the js file <body> tag, which enables faster loading the browser page
Statement (statement)

Recommendations add a semicolon at the end of each statement, doing so make the code easier to read. Let each statement on a separate line approach can more easily track the order of execution of JavaScript scripts, such as

first statement；
second statement；

2.1 annotation (comment)

// a single line comment
/ * Multiline
comment
* /
<-! HTML single-line comment ->, JavaScript is not required to do so, it will "->" as part of contents Notes, Note:
HTML allowed above <- -> comment span multiple lines, but! each row requires JavaScript must be at the beginning of this comment with "<! -" as a sign.
** Summary: To avoid confusion, we recommend using the "//" when the line is annotated with "/ *" comment multiple lines **

2.2 Variable (variable)

The value of the deposit operation is called assignment

mood = "happy";
age = "22";

After a variable is assigned, say, the variable contains the word. Variable mood now contains the value "happy", now contains the variable age 22

Note : JavaScript allows direct assignment of variables without prior declaration (declare), in JavaScript is not declared before assignment to a variable, the assignment will automatically declare the variable. Although JavaScript does not have to be forced to declare variables in advance, but to declare variables in advance is a good programming practice.
A statement once again declare multiple variables and assignment completion

var mood = "happy";
var age = "22";
或
var mood = "happy",age = "22";

In JavaScript, variables, and names of other syntax elements are case sensitive.
- JavaScript variable names are not allowed variable names contain spaces or punctuation marks ($ exception )
- Allowed to contain letters, numbers, dollar signs, and underscores ( but do not allow the first character is a number ). In order to compare greedy variable name with easy to read, you can then insert the variable name in place an underscore, such as
```
var my_mood = "happy";
```
One way is to use the exception camelCased, such as

var myMood = "mood";

Usually hump format is the preferred format function names, method names, and object properties named after.

"JavaScript DOM programming art" (second edition) study notes (a)

Guess you like