如何在多个文件之间共享全局变量？

Question

I have two files that both need a global variable. I have a click button. When it's clicked, runs a function. The code looks like this:

file1:

var globalVar = '', // The global variable

<button onClick = {() => this.edit(arg1)}></button>
function edit (arg1){

   globalVar = arg1;
}

module.exports = globalVar;

I have another file, looks like this:

file2:

var globalVar = require(./file1);

function openModal(){

if (globarVar != ''){
 do something

} }

The issue is that when I click button, the globalVar is updated in the edit() function, but I console.log(globalVar) in file2 it shows ' '.My question is how do I pass the globalVar to file2 when I click the button?

Answer 1

If you truly want a global variable (not advisable, of course) then you're always 100% free to do

window.globalVar = 0;

in any of your modules.

---

The more robust solution would of course be to have this global variable sit in some sort of dedicated module, like

globalVar.js

export default {
    value: 0
};

and then you could

import globalVal from './globalVar';

globalVal.value = 'whatever';

from any modules needed.

The only risk would be that webpack might duplicate this same "global" value into multiple bundles if you're code splitting, depending on your setup. So separate module would be using their own local copy of this not-so-global variable. EDIT - this isn't true. webpack never did this; that comment was based on a misunderstanding on my part.