let {parse} = require("acorn")

module.exports = function(code) {

let ast

try { ast = parse(code) }

catch(_) { return code }

let patches = []

ast.body.forEach(node => {

if (node.type == "VariableDeclaration" && node.kind != "var")

patches.push({from: node.start, to: node.start + node.kind.length, text: "var"})

if (node.type == "ClassDeclaration")

patches.push({from: node.start, to: node.start, text: "var " + node.id.name + " = "})

})

patches.sort((a, b) => a.from - b.from || (a.to || a.from) - (b.to || b.from))

let out = "", pos = 0

patches.forEach(({from, to, text}) => {

out += code.slice(pos, from) + text

pos = to

})

out += code.slice(pos)

return out

}