JavaScript: Syntax rules for declaring variable names

I. Rules of grammar

1. The variable must start with a letter, an underscore (_), or a dollar ($) symbol.

2. You can then use any number of English letters, numbers, underscores (_), or dollar ($) characters.

3. Cannot use JS keyword and reserved word.

Ii. examples

VAR score;

score= "100";

Third, attention

1.JS is case-sensitive. such as variable score and score are not the same, quite two variables.

2. Although variables can not be declared, directly used, but not standardized, will involve variable name promotion and other issues.

JavaScript: Syntax rules for declaring variable names