JavaScript variable naming rules _ basic knowledge

You must know and pay attention to js learning. In fact, every language has its naming rules. JScript is a case-sensitive language.

The first character must be an ASCII letter (both uppercase and lowercase) or an underscore (_). Note that the first character cannot be a number.
The subsequent characters must be letters, numbers, or underscores.
Variable names must not be reserved words.

The following are examples of valid variable names:
_ Pagecount Part9 Number_Items some examples of invalid variable names are given below:

99 Balloons // cannot start with a number. The Smith & Wesson // "and" symbol (&) is invalid for variable names.