patternjavascriptModerate

Advice needed for scopes in JavaScript

Submitted by: @import:stackexchange-codereview·Mar 10, 2026·

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neededjavascriptscopesadvicefor

Problem

I would like to connect this "JS" to Bugzilla (example: bugzilla.mozilla.org or landfill.bugzilla.org).

I started to learn JS language today and I would like to ask you:

How can I not do bad things in global scope?

How should I use functions (in var or not)?

```
quicksearch = document.getElementById('quicksearch_top');
comment = document.getElementById('comment');

severity = document.getElementById('bug_severity');
priority = document.getElementById('priority');

commit_top = document.getElementById('commit_top');
commit = document.getElementById('commit');

function focusonload() {
// may be it should be
// in next function?

function cursorfocus(s) {
x = window.scrollX;
y = window.scrollY;
s.focus();
window.scrollTo(x, y);
}

if (comment !== null) {
cursorfocus(comment)
} else {
quicksearch.focus();
}
}

function navigation(keypressed) {

keypressed = keypressed || window.event;

function selectelement(w, select) {
w.value = select;
}

keyCode = keypressed.keyCode || keypressed.which,
kn = {
enter: 13,
save: 83,
down: 40,
up: 38,
p1: 49,
p2: 50,
p3: 51,
p4: 52,
p5: 53,
};

if (keypressed.altKey) {
if (keyCode == nk.save && commit_top!==null){
commit_top.click();
}

var key_str;
if (priority!==null){
switch (keyCode) {
case kn.p1: key_str = "P1"; break;
case kn.p2: key_str = "P2"; break;
case kn.p3: key_str = "P3"; break;
case kn.p4: key_str = "P4"; break;
case kn.p5: key_str = "P5"; break;
}
}
selectelement(priority, key_str);
severity.focus();

} else if (keypressed.ctrlKey) {
switch (keyCode) {
case kn.enter:
if (commit!==null&&comment.value!=="") {

Solution

How can I not mess up the global scope?

You can use an IIFE ( Immediately Invoked Function Expression ) to surround your code and then assign all your variables with var commitTop

quicksearch -> quickSearch

selectelement -> selectElement

etc.etc

Your keycode map is very nice, keep it that way!

One last comment is that you should not use document.onkeydown = navigation;, there is a good chance that you will break something this way.

Try document.addEventListener("keydown", navigation, true); instead.

Code Snippets

(function(){

  var quicksearch = document.getElementById('quicksearch_top');
  var comment = document.getElementById('comment');

  var severity = document.getElementById('bug_severity');
  var priority = document.getElementById('priority');

  var commit_top = document.getElementById('commit_top');
  var commit = document.getElementById('commit'); 

  //the rest of your code here

}());

Context

StackExchange Code Review Q#40462, answer score: 10

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