如果我不知道 javascript 中的完整变量名，如何找到变量/数组

Question

I am trying to get additional information from site and there is variable/array that defined randomly. Like this:

var firstvar_numbers= "already exist"
var secondvar_numbers= ["a","b","c","d"]

numbers is random value that given by site. In firefox DOM when I wrote half of secondvar_ it immediately find that I wanted because there is only one variable that starts with second . My question is how I can get value/array of variable in userscript/javascript by knowing part of the variable. Example if you don't understood: Html

//Variable that I need from server
<div id="variables" class="container">

<script type="text/javascript">
var exists_73647286="hello world"

var array_636353=[62,96,11,28]
</script>
</div>

Javascript

//Code that will get array
alert("exists_"+seconpartofvar())
function seconpartofvar(){your code}

OR

alert(autocomplate.exists_)

Here I can write alert(exists_) in Firefox console and it will recommend autocomplate.

Answer 1

Since it's declared with var on the top level, you can iterate over the properties of the window and find one which startsWith what you're looking for:

 // Example site code: var array_636353 = [62, 96, 11, 28]; // Userscript code: const prop = Object.keys(window).find(key => key.startsWith('array_')); console.log(prop, window[prop]);