💻
How are you using Babel?
@babel/cli
Input code
(async function () {
console.log('XXXXXXX This is side effect.')
})();
(async function () {
console.log('YYYYYYY This is side effect but marked as pure.')
}).apply();
(async function () {
console.log('ZZZZZZZ This is side effect but marked as pure.')
}).call();Configuration file name
No response
Configuration
In Babel Playground, check "force all transforms."
Current and expected behavior
Diff for readability
Red is current. Green is expected.
function asyncGeneratorStep(n, t, e, r, o, a, c) { try { var i = n[a](c), u = i.value; } catch (n) { return void e(n); } i.done ? t(u) : Promise.resolve(u).then(r, o); }
function _asyncToGenerator(n) { return function () { var t = this, e = arguments; return new Promise(function (r, o) { var a = n.apply(t, e); function _next(n) { asyncGeneratorStep(a, r, o, _next, _throw, "next", n); } function _throw(n) { asyncGeneratorStep(a, r, o, _next, _throw, "throw", n); } _next(void 0); }); }; }
_asyncToGenerator(function* () {
console.log('XXXXXXX This is side effect.');
})();
- /*#__PURE__*/_asyncToGenerator(function* () {
+ _asyncToGenerator(function* () {
console.log('YYYYYYY This is side effect but marked as pure.');
}).apply();
- /*#__PURE__*/_asyncToGenerator(function* () {
+ _asyncToGenerator(function* () {
console.log('ZZZZZZZ This is side effect but marked as pure.');
}).call();Environment
Possible solution
No response
Additional context
After Babel wrongly marked the function call as pure, Terser will remove the function as it thinks it's dead code.
Terser output
Via try.terser.org.
function n(n,o,t,e,i,r,c){try{var u=n[r](c),f=u.value}catch(n){return void t(n)}u.done?o(f):Promise.resolve(f).then(e,i)}function o(o){return function(){var t=this,e=arguments;return new Promise((function(i,r){var c=o.apply(t,e);function u(o){n(c,i,r,u,f,"next",o)}function f(o){n(c,i,r,u,f,"throw",o)}u(void 0)}))}}o((function*(){console.log("XXXXXXX This is side effect.")}))();And prettifying Terser result.
function n(n, o, t, e, i, r, c) {
try {
var u = n[r](c),
f = u.value;
} catch (n) {
return void t(n);
}
u.done ? o(f) : Promise.resolve(f).then(e, i);
}
function o(o) {
return function () {
var t = this,
e = arguments;
return new Promise(function (i, r) {
var c = o.apply(t, e);
function u(o) {
n(c, i, r, u, f, "next", o);
}
function f(o) {
n(c, i, r, u, f, "throw", o);
}
u(void 0);
});
};
}
o(function* () {
console.log("XXXXXXX This is side effect.");
})();
💻
How are you using Babel?
@babel/cli
Input code
Configuration file name
No response
Configuration
In Babel Playground, check "force all transforms."
Current and expected behavior
Diff for readability
Red is current. Green is expected.
function asyncGeneratorStep(n, t, e, r, o, a, c) { try { var i = n[a](c), u = i.value; } catch (n) { return void e(n); } i.done ? t(u) : Promise.resolve(u).then(r, o); } function _asyncToGenerator(n) { return function () { var t = this, e = arguments; return new Promise(function (r, o) { var a = n.apply(t, e); function _next(n) { asyncGeneratorStep(a, r, o, _next, _throw, "next", n); } function _throw(n) { asyncGeneratorStep(a, r, o, _next, _throw, "throw", n); } _next(void 0); }); }; } _asyncToGenerator(function* () { console.log('XXXXXXX This is side effect.'); })(); - /*#__PURE__*/_asyncToGenerator(function* () { + _asyncToGenerator(function* () { console.log('YYYYYYY This is side effect but marked as pure.'); }).apply(); - /*#__PURE__*/_asyncToGenerator(function* () { + _asyncToGenerator(function* () { console.log('ZZZZZZZ This is side effect but marked as pure.'); }).call();Environment
Possible solution
No response
Additional context
After Babel wrongly marked the function call as pure, Terser will remove the function as it thinks it's dead code.
Terser output
Via try.terser.org.
And prettifying Terser result.