动态载入js

1. var lajax={}; 2. var __count__ = 0; 3. lajax.getXmlHttp = function(){ 4. var xmlHttp = null; 5. try { 6. xmlHttp = new XMLHttpRequest(); 7. } 8. catch (e) { 9. var progIds = ['MSXML2.XMLHTTP', 'Microsoft.XMLHTTP', 'MSXML2.XMLHTTP.5.0', 'MSXML2.XMLHTTP.4.0', 'MSXML2.XMLHTTP.3.0']; 10. var success = false; 11. for (var iterator = 0; (iterator < progIds.length) && (!success); iterator++) { 12. try { 13. xmlHttp = new ActiveXObject(progIds[iterator]); 14. success = true; 15. } 16. catch (e) { 17. } 18. } 19. if (!success) { 20. return null; 21. } 22. } 23. return xmlHttp; 24. }; 25. 26. lajax.sendRequest = function(method,url,requestData,callBack) 27. { 28. var xmlHttp = lajax.getXmlHttp(); 29. xmlHttp.open(method,url,true); 30. if (method=="POST") xmlHttp.setRequestHeader('Content-type', 'application/x-www-form-urlencoded'); 31. xmlHttp.onreadystatechange = function() 32. { 33. if (xmlHttp.readyState == 4) { 34. if (xmlHttp.status == 200) { 35. callBack(xmlHttp); 36. } 37. } 38. } 39. if (method=="POST") xmlHttp.send(requestData); 40. else xmlHttp.send(null); 41. } 42. lajax.loadJS = function(jsPath, callBack) { 43. var _callBack = function(xmlHttp) { 44. __count__++; 45. _includeJS("js" + __count__, xmlHttp.responseText); 46. callBack(); 47. } 48. lajax.sendRequest('GET',jsPath, null, _callBack); 49. } 50. 51. function _includeJS(sId, source) { 52. if (( source != null ) && (!document.getElementById(sId))){ 53. var oHead = document.getElementsByTagName('HEAD').item(0); 54. var oScript = document.createElement( "script" ); 55. oScript.language = "javascript"; 56. oScript.type = "text/javascript"; 57. oScript.id = sId; 58. oScript.defer = true; 59. oScript.text = source; 60. oHead.appendChild(oScript); 61. } 62. }