VSCode扩展在函数外部使用变量

Question

Hello within a vscode extension.js I cannot use the variable "chunk" outside of the function it is inside of:

let http = require('http');
let keyname = "key.key";
http.get('http://mysite.nl/vscode/?with=data', function(res) {
  res.on("data", function(chunk) {
    vscode.window.showInformationMessage("INSIDE: " + chunk);
  });
});
vscode.window.showInformationMessage("OUSIDE FUNCTION:" + chunk); /*this does not work*/

edit: (tried to make a global variable, but I fail so much at javascript, is this supposed to work?)

let globalvar;
let http = require('http');
let keyname = "key.key";
http.get('http://mysite.nl/vscode/?with=data', function(res) {
  res.on("data", function(chunk) {
    vscode.window.showInformationMessage("INSIDE: " + chunk);
    globalvar = chunk;
  });
});
vscode.window.showInformationMessage("OUSIDE FUNCTION:" + globalvar); /*this does not work*/

Answer 1

It doesn't work for two reasons. First of all, function arguments are local to the function they belong to:

 function foo(bar) { console.log("Inside function: %s", typeof bar); function inner(){ console.log("In function's scope: %s", typeof bar); } inner(); } foo("Hi"); console.log("Elsewhere: %s", typeof bar); 

Secondly, http.get() starts fetching the URL in another thread and continues executing the rest of the program, ie it calls vscode.window.showInformationMessage() immediately. The variable does not even exist yet so, even if you didn't have scope issues, there would be nothing to print. Then, some time later (even if only a few milliseconds) the GET request completes. If it succeeded then function(chunk) {} gets finally called—too late!

 let globalvar; window.setTimeout(function (chunk){ console.log("Done! Chunk is %s", chunk); globalvar = chunk; }, 2000, "Hi!"); console.log("Chunk? %s", typeof globalvar);