JS Syntax Basics

1. Identifiers

The so-called identifiers are names of variables, arrays, functions, etc.

The naming of identifiers requires following a certain naming convention

2. Naming rules are divided into two categories: rigid requirements, soft requirements

The so-called rigid requirements, means that must be observed, if not complied with, even the program can not run

Soft requirements: Not required to comply with, but is an unwritten rule of the industry

mandatory Requirements specific rules :

Consists of letters, numbers, underscores, and $, but cannot start with numbers

Disable the use of keywords and reserved words inside ES

Case sensitive

Soft Requirements : hope to know the meaning of the text

You can tell what this identifier means by using an identifier name.

naming laws :

Hump nomenclature : The Hump naming method is divided into two kinds: the big Hump and the small hump . The so-called Big Hump (Pascal nomenclature) means that each word is capitalized, for example: UserName the so-called small hump, the first letter lowercase, and the first letter of the following words for example: UserName

Hungarian nomenclature :

The so-called Hungarian nomenclature is made up of one or more words, preceded by a fixed prefix

Array (arrays) A_myuser

Boolean (Boolean) b_ispassed

function (functions) fn_dosth

Object (objects) O_person

Snake Name method

The so-called serpentine nomenclature refers to the use of underscores to separate each word.

User_name User_password

3. The comments inside ES

There are two types of annotations, one single-line comment and the other a multiline comment

single-line comment : Starts with two slashes

Multiline Comment : Start with/* and end with */

4. Strict mode

Starting with ES5, a reference to something called strict mode. As the name implies, is more stringent, in this mode, will reduce the ambiguity of the syntax, and parsing faster. Also, the syntax supported under strict mode can often be seen as the reference standard for the next version.

How to enter strict mode

"Use Strict"

5. JS statement

Like most programming languages, they end with semicolons, but this is not a must

Although semicolons can be omitted, they are not recommended. Because the compressed file compresses the code, it can cause code errors if there is no semicolon.

6. Keywords and reserved words

Keywords: the so-called keyword, refers to the ES inside the predefined identifiers, you can not use these keywords when you name

Keywords (ES5 for example) are : Break/do/instanced/typeof/case/else/new/var/catch/finanly/return/void/continue/for/switch /while/debugger/function/this/with/default/if/throw/delete/in/try

reserved Words (ES5 for example) are : abstrac/enum/int/short/boolean/export/interface/static/byte/extends/long/super/char/final /native/synchronized/class/float/package/throes/const/goto/private

/transient/debugger/implements/protected/volatile/double/import/public

JS Syntax Basics