How can use global let declaration in ES6?

Question

How I can use ES6 global let declaration?

let video = document.getElementById("video");
let button = document.getElementById("controllbutton");

The Above code causes Error that SyntaxError: missing ; before statement SyntaxError: missing ; before statement on Firefox.

Why above code causes Syntax Error?

Answer 1

Are you transpiling? I don't see browser support for FF for this feature: https://kangax.github.io/compat-table/es6/

Answer 2

我在脚本标记中添加了type="application/javascript;version=1.7" ，它解决了语法错误。