JavaScript dynamic insertion script basic ideas and functions

In daily front-end development, occasionally there is a need to dynamically insert javascript code, the basic idea is:

1. Dynamically create a script tag, set its SRC attribute, type attribute, etc

2. Insert the script node into the page and load the js file

Is equivalent to will < The script type = "text/javascript" SRC = "XXX. Js >" < / script> Added to the page, but the process is done dynamically, this is deliberately encapsulated a function to achieve:

 
//Insert script tags dynamically
function createScript(url, callback){ 
var oScript = document.createElement('script'); 
oScript.type = 'text/javascript'; 
oScript.async = true; 
oScript.src = url; 
/* 
** script Of the label onload and onreadystatechange The event  
** IE6/7/8 support onreadystatechange The event  
** IE9/10 support onreadystatechange and onload The event  
** Firefox/Chrome/Opera support onload The event  
*/ 

//Judge IE8 and the following browsers
var isIE = !-[1,]; 
if(isIE){ 
alert('IE') 
oScript.onreadystatechange = function(){ 
if(this.readyState == 'loaded' || this.readyState == 'complete'){ 
callback(); 
} 
} 
} else { 
//IE9 and above, Firefox, Chrome, Opera
oScript.onload = function(){ 
callback(); 
} 
} 
document.body.appendChild(oScript); 
} 

Usage:

 
createScript('xxx.js', function(){ 
console.log('OK'); 
});