Utilities.js from Larry Ullman's Modern JavaScript

utilities.js

// Utilities.js from Larry Ullman's Modern JavaScript

var U = {
  $: function(id) {
    'use strict';
    
    if (typeof id == 'string') {
      return document.getElementById(id);
    }
  }, // end $()
  
  setText: function(id, message) {
    'use strict';
    
    if ( (typeof id == 'string') && (typeof message =='string') ) {
      var output = this.$(id);
      
      if (!output) return false;
      
      if (output.textContent !== undefined) {
        output.textContent = message;
      }
      else {
        output.innerText = message;
      }
      return true;
    } // end main if
  }, // end setText()
  
  addEvent: function(obj, type, fn) {
    'use strict';
    
    if (obj && obj.addEventListener) {
      obj.addEventListener(type, fn, false);
    }
    else if (obj && obj.attachEvent) {
      obj.attachEvent('on' + type, fn);
    }
  }, // end addEvent()
  
  removeEvent: function(obj, type, fn) {
    'use strict';
    
    if (obj && obj.removeEventListener) {
      obj.removeEventListener(type, fn, false);
    }
    else if (obj && obj.detachEvent) {
      obj.detachEvent('on' + type, fn);
    }
  } // end of removeEvent()
}; // end of U declaration