I searched for this, but I keep finding issues regarding
"<scr" + "ipt>"
My issue is that I want to generate some JavaScript code from my JavaScript code.
I have copied a general idea below. How can what I want be achieved? Is it necessary to use an external .js file?
document.write("var testprompt = prompt('What zindex page to change?');
var getpage = getElementById('mobileimage'+testprompt);
getpage.style.zIndex = '1000';");
You are looking for eval(). I would, however, advise against using it as there are many security problems with running JavaScript code using eval. See Why is using the JavaScript eval function a bad idea?.
The problem with using JavaScript to write JavaScript is that the browser will only execute the first pass over the code.
The JavaScript written with document.write() will not be executed, thus rendering it quite useless. Why can't you simply write the JavaScript you want to execute as JavaScript instead of abstracting it through document.write()?
This works for me:
<html>
<body>
<script>
var i = 1;
document.write(i);
document.write("<scr" + "ipt> i = 2; document.write(i); </scr" + "ipt>");
i = 3;
document.write(i);
</script>
123
</body>
</html>
Run it in a single line without '\n' between the string. It works.
document.write("var testprompt = prompt('What zindex page to change?'); var getpage = getElementById('mobileimage' + testprompt); getpage.style.zIndex = '1000';");
getElementById() works only after the DOM is loaded, while the code written via document.write() is executed immediately as the HTML document is parsed.
You have to encapsulate your code in a callback to be executed after the DOM is loaded (I suggest to use a library like jQuery).
document.writeto generate a completely new page (document.open/write/close). New pages do not preserve the Javascript from the old page, so you need to write new ones.