optimized function changes behavour

[roblan]

• Operating System: Mac OS
• Node Version: 11.9.0
• NPM Version: 6.8.0
• webpack Version: 4.29.5
• terser-webpack-plugin Version: 1.2.3

Expected Behavior

function should behave like non minimized one.

Actual Behavior

Terser plugin overoptimize function and changes it return params.

Code

module.exports = (function(constructor) {
  return constructor();
})(function() {
  return function(input) {
    var keyToMap = input.key;
    return {
      mappedKey: (function(value) {
        return value || "CONDITIONAL_DEFAULT_VALUE";
      })(keyToMap)
    };
  };
});

How Do We Reproduce?

https://github.com/roblan/webpack_terser_bug/tree/master

[alexander-akait]

We just wrapper around terser, please post issue in terser repo

[roblan]

@evilebottnawi - but code parsed through terser works just fine

[alexander-akait]

@roblan we don't change code, only send to terser and return, maybe other plugin do this

[roblan]

@evilebottnawi have you looked into provided example? only difference is minimizer: [new TerserPlugin()] in webpack config

[alexander-akait]

@roblan yes, and as i said above we don't change you code, all optimizations do terser, if some optimizations break code or do something wrong please post issue in terser repo https://github.com/terser-js/terser

[roblan]

ok, thanks. just realised that flags --compress --mangle makes all the difference here