Valid Variable Names

When creating variables, the variable name must always start with a letter and cannot contain spaces, though numbers and underscores are allowed to be contained in it also.

Create a function which returns true if a given variable name is valid, otherwise return false.

Examples

variableValid("result") ➞ true

variableValid("odd_nums") ➞ true

variableValid("2TimesN") ➞ false

Notes

• Inputs are given as strings.
• Variable names with spaces are not allowed.
• Although this question may seem like otherwise, you can't actually assign words with quotes around them as variables.
• The rules exposed in this challenge are an oversimplification on how variable and identifier names are considered valid in JavaScript.