Variable created in catch(err) overrides external variable

[fregante]

(function() {
    var e = 'I’m gooooooooone!';
    return (function () {
        console.log(e)
        try {} catch (e) {}
    })()
}());

Results in:

I’m gooooooooone!

But it's minified to:

!function(){return function(){console.log(t);try{}catch(t){}}()}();

which results in:

Uncaught ReferenceError: t is not defined(…)

Tested on: https://github.com/Skalman/UglifyJS-online

[avdg]

Please update uglify to the latest version

[avdg]

Also, reproducible on master, so this is actually a valid bug report. Uh variable is defined, so no bug on master. It's just using the same mangle variable.

[avdg]

https://avdg.github.io/uglify.html#editor__x28function_x28_x29_s0_x7b_r_n_s3var_s0e_s0_x3d_s0_x27I_u2019m_s0gooooooooone_x21_x27_x3b_r_n_s3return_s0_x28function_s0_x28_x29_s0_x7b_r_n_s7console_x2elog_x28e_x29_r_n_s7try_s0_x7b_x7d_s0catch_s0_x28e_x29_s0_x7b_x7d_r_n_s3_x7d_x29_x28_x29_r_n_x7d_x28_x29_x29_x3b

[fregante]

hmm I was actually about to close it because it doesn't seem to appear in 2.7.0 and 2.7.3

$ uglifyjs --version
uglify-js 2.6.4
$ uglifyjs a.js --compress unused
WARN: Dropping unused variable e [a.js:2,8]
!function(){return function(){console.log(e);try{}catch(e){}}()}();

$ uglifyjs --version
uglify-js 2.7.3
$ uglifyjs a.js --compress unused
!function(){var e="I’m gooooooooone!";return function(){console.log(e);try{}catch(e){}}()}();

Is there a regression?

[fregante]

Cool, closing then :)

[kzc]

@bfred-it First I'd like to congratulate you for filing Issue 1337. You can claim your prize at the door.

Your test case is a --support-ie8 bug - a.k.a. screw_ie8=false.

--support-ie8 used to be the default for uglify-js@2.6.x and earlier.

The default for uglify-js@2.7.x is now --screw-ie8. See #409 (comment) and #1179.

$ uglifyjs -V
uglify-js 2.7.3

$ cat a.js
(function() {
    var e = 'I’m gooooooooone!';
    return (function () {
        console.log(e)
        try {} catch (e) {}
    })()
}());

--support-ie8

$ uglifyjs a.js --support-ie8 -cm
WARN: Dropping unused variable e [a.js:2,8]
!function(){return function(){console.log(n);try{}catch(n){}}()}();

$ uglifyjs a.js --support-ie8 -cm | node
WARN: Dropping unused variable e [a.js:2,8]
[stdin]:1
!function(){return function(){console.log(n);try{}catch(n){}}()}();
                                          ^

ReferenceError: n is not defined

--screw-ie8

$ uglifyjs a.js --screw-ie8 -cm
!function(){var o="I’m gooooooooone!";return function(){console.log(o);try{}catch(o){}}()}();

$ uglifyjs a.js --screw-ie8 -cm | node
I’m gooooooooone!

$ uglifyjs a.js -cm | node
I’m gooooooooone!

[fregante]

Gotcha! Thanks for the explanation!