How to Add or Remove the javascript file using javascript function

We can use following functions for adding the Javascript file dynamically.

function AddJsFile(file) {
var script  = document.createElement('script');
script.src  = file;
script.type = 'text/javascript';
script.defer = true;

document.getElementsByTagName('head').item(0).appendChild(script);
}

Or We can use this also, both will work:
function AddJsFile(file)
{
document.write('');
}

We can use following functions for adding the CSS file dynamically.

function AddCssFile(file) {
var stylesheet  = document.createElement('link');
stylesheet.href  = file;
stylesheet.type = 'text/css';
stylesheet.defer = true;

document.getElementsByTagName('head').item(0).appendChild(stylesheet);
}

Or We can use this also, both will work:

function AddCssFile(file)
{
document.write('');
}

We can use the following code for remving the JS the files.

function RemoveJsFile(file) {
var alljs = document.getElementsByTagName("js")
for (var i = alljs.length; i >= 0; i--) {
if (alljs[i] && alljs[i].getAttribute("src")!= null && alljs[i].getAttribute("src").indexOf(file)!=-1)

alljs[i].parentNode.removeChild(alljs[i])
}

}

We can use the following code for remving the CSS the files.

function RemoveCssFile(file) {
var allcss = document.getElementsByTagName("css")
for (var i = alljs.length; i >= 0; i--) {
if (allcss[i] && allcss[i].getAttribute("href")!= null && allcss[i].getAttribute("href").indexOf(file)!=-1)

allcss[i].parentNode.removeChild(allcss[i])
}

}