当代码为字符串时，重新编译Javascript ES6至ES5代码

Question

I tried using facebook's Regenerator to convert ES6 code to ES5 code. The code I need to convert is produced by React-ace editor and it is a string. Regenerator does not recognize strings and simply returns them as it was.

I tried using eval() and new Function(), both of which will be executed when passed into regenerator.compile("whatever code I need to compile").code, and the value returned will just be the return value of the executed code.

Is there a way to convert the string produced by React-ace(or any browser text editor) and converted it to ES5 code? Are there any other libraries that allows you to convert ES6 syntax to ES5?

Working Example with local function declaration:

let testFunction = (b) => {

  let a = (c) => {
    return c
  }

  return b;
}

let regenCode = require('regenerator').compile(testFunction).code;
console.log(regenCode);

this will produce:

function testFunction(b) {

   var a = function (c) {
     return c;
   } 

   return b;
}

Trying to do:

let regenCode = require('regenerator').compile("let testFunction = (b) => { let a = (c) => { return c } return b; }");

but this will simply give the string back to me

Answer 1

You can only use Regenerator programmatically with an AST , not with a string.

From the Regenerator documentation :

AST transformation:

 var recast = require("recast"); var ast = recast.parse(es6Source); ast = require("regenerator").transform(ast); var es5Source = recast.print(ast); 

In your case, you'd have to do something like:

var recast = require("recast");
var ast = recast.parse("let testFunction = (b) => { let a = (c) => { return c }; return b; }");
ast = require("regenerator").transform(ast);
var es5Source = recast.print(ast);