constant-folding template strings

[mariusGundersen]

There is a bug in the babel-plugin-minify-constant-folding package where it incorrectly inlines template strings. Here is a simple example:

const a = ["a", "b"].join(' ');
// -> const a="a b";


const b = [`a${a}`, `b${a}`].join(' ');
// -> const b=" ";

In the second example it should keep the interpolation and produce a template string, but it does not, instead returning just an empty string. The result is broken code.

[vigneshshanmugam]

@mariusGundersen Thanks for creating the issue, #613 should fix this

[mgol]

This has just hit me in production. A very simple complete test case:

const a = 'a';
console.log([`${ a }b`, 'c',].join(''));

transpiles to:

const a='a';console.log('c');

instead of the expected:

const a='a';console.log(`${ a }bc`);

or:

console.log('abc');

Perhaps the PR should include a test like that.

[lydell]

Could this please be released to npm? @boopathi?