warn on empty jquery selection badSelectorAction devinrhode2

StrictjQuery3.js

// simple working copy pasta version (requires extendFunction.js, devinrhode2/extendFunction.js
// https://github.com/devinrhode2/extendFunction.js

window.failsafe = 'failsafe';

  // Don't like throwing errors? Define $.badSelectorAction to be whatever you want.
  function badSelectorAction( selector, context, originalResult ) {
    if (window.console && console.warn) {
      console.warn( '$(\''+selector+'\') selected nothing. Do $(sel, "failsafe") to silence warning. Context:', context);
    }
    return originalResult;
  }
  $.badSelectorAction = badSelectorAction;

  //Feel free to stop reading here!
  extendFunction('$', function strictSelectorOverride( args, oldjQuery ) {
    var selector = args[0];
    var context = args[1];

    //if it's not a string or clearly html..
    if ( typeof selector !== 'string' ||
         ( selector.charAt(          0          ) === '<' &&
           selector.charAt( selector.length - 1 ) === '>' &&
           selector.length >= 3 )
       )
    {
      return oldjQuery.apply(this, arguments);
    }

    if ( context === 'failsafe' ) {
      return oldjQuery.call(this, selector); //don't do apply because context is 'failsafe'
    } else {
      var result = oldjQuery.apply(this, arguments);
      if (typeof result.length === 'number') {
        if (result.length > 0) {
          return result;
        } else {
          return $.badSelectorAction.call(this, selector, context, result);
        }
      } else {
        //.length is undefined or not a number, result is unknown, just return it.
        return result;
      }
    }
  });