JSFiddle - React, Tailwind, and code Playground

by yi hom

JavaScript

var a = 1;
var b = 2;

function example() {
  var b = 3;
  a += b;
//js在函式中如果找不到宣告會從外部找，C則無法編譯(a沒有被定義)
}

example();

a; // 4
b; // 2

document.write(a+"<br>"+b);