isdefined() #javascript

isdefined.js

/**
 * tests for all the ways a variable might be undefined or not have a value
 * @param {*} x the variable to test
 * @return {Boolean} true if variable is defined and has a value
 */
function isDefined(x) {
    if ( x === '' || x === null || x === undefined) {
        return false;
    }
    return true;
}