function isAlphaDigit(subject) {
    var subjectString = coerceToString(subject);
    return REGEXP_ALPHA_DIGIT.test(subjectString);
  }
Checks whether `subject` contains only alpha and digit characters.

@function isAlphaDigit
@static
@since 1.0.0
@memberOf Query
@param {string} [subject=''] The string to verify.
@return {boolean} Returns `true` if `subject` contains only alpha and digit characters or `false` otherwise.
@example
v.isAlphaDigit('year2020');
// => true

v.isAlphaDigit('1448');
// => true

v.isAlphaDigit('40-20');
// => false