While naming your variables in JavaScript keep following rules in mind.
You should not use any of the JavaScript reserved keyword as variable name. These keywords are mentioned in the next section. For example, break or boolean variable names are not valid.
JavaScript variable names should not start with a numeral (0-9). They must begin with a letter or the underscore character. For example, 123test is an invalid variable name but _123test is a valid one.
JavaScript variable names are case sensitive. For example, Name and name are two different variables.