Error: 'import' and 'export' may appear only with 'sourceType: "module"'

[zhanzhenzhen]

Ran into this error, then renamed file to ".mjs", but still got this error:

$ npx minify fff.mjs --mangle.topLevel --outFile fff.min.mjs
SyntaxError: unknown: 'import' and 'export' may appear only with 'sourceType: "module"' (1:0)
Consider renaming the file to '.mjs', or setting sourceType:module or sourceType:unambiguous in your Babel config for this file.

> 1 | export let aaa = function(){};
    | ^
  2 |

Environment: Node.js v10.1

[boopathi]

The default sourceType is script and the Node API exposes it. The CLI doesn't yet have this option.

[matthewp]

Hey @boopathi I don't believe that fixes it. The error says:

Consider renaming the file to '.mjs', or setting sourceType:module or sourceType:unambiguous in your Babel config for this file.

The file does have the .mjs extension. So the sourceType shouldn't be required, right?

[asakusuma]

@boopathi I'm running into the same issue. My file extension is .mjs, but I'm still getting the same error. Also, setting sourceType in .babelrc doesn't seem to fix the issue either.

[asakusuma]

My workaround was to directly use babel.transformSync

const minifyPreset = require('babel-preset-minify');
const babel = require('@babel/core');
const fs = require('fs');
const args = process.argv.slice(2);
if (args.length !== 2) {
  throw new Error('Must pass two arguments, input and output filename');
}

const { code } = babel.transformSync(fs.readFileSync(args[0]), {
  minified: true,
  sourceType: "module",
  configFile: false,
  presets: [[minifyPreset]]
});

fs.writeFileSync(args[1], code);

[TianyiShi2001]

I'm still getting the same issue

[cbuteau]

Same problem...uninstalling...

[el-hackerino]

Same here still. The file does have the .mjs extension. Sad.