fengari
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fengari-lua
string.format() doesn't work under IE 11
Fengari is said to be "Verified to work in Microsoft IE 11". But unfortunately an error is raised under IE 11:
print(("%02X"):format(0)) TypeError: Object doesn't support property or method 'repeat'
It seems that the sprintf.js which implements string.format is not IE11-compatible.
The problem is in the single line of code:
pad = ph.width ? (pad_length > 0 ? pad_character.repeat(pad_length) : '') : ''
Unfortunately, repeat is not implemented on all IE, including IE11
BTW .repeat occurs also in lstrlib.js.
Support of IE11 actually means support of Windows 7 users. There are a lot of them nowadays.
All what is needed for happiness is to implement String.prototype.repeat manually in Fengari.
Note to self: see core-js implementation https://github.com/zloirock/core-js/blob/master/packages/core-js/internals/string-repeat.js#L12
I can't modify the global environment
But why? Defining standard well-known (but undefined on IE) function looks very innocent.
I've worked in environments before where the rule is never modify the global JS environment. I want fengari to be allowed in such environments.
Every modification you make is potentially conflicting with some other piece of JS running on a site. The easiest solution is to just opt out.
Probably, this issue should be migrated from fengari to fengari-web, because it affects only fengari running inside browser.
The bug hasn't been solved in three months. Maybe, the documentation should honestly claim that Fengari does require a polyfill for IE11?
I've been hoping that https://github.com/alexei/sprintf.js/pull/183 will get merged.
Otherwise I may just remove that dependency entirely and implement our own sprintf-alike.
I haven't had the time to implement out own sprintf, so I'm marking this issue as "help-wanted". If anyone would like to implement it, please send a PR!
Would it be fine just to fork + vendor sprintf.js with your fix?
I guess. But there is plenty of code in there we don't use. And the verification code in lstrlib.js sort of duplicates some of the work anyway. A rewrite with a bit of "inspiration" is probably the best choice.
I can't modify the global environment
But why? Defining standard well-known (but undefined on IE) function looks very innocent.
You pollute users namespace. It's considered a bad practice. It's much easier to point users that it's not working on this and that browser and offer a link to a polyfill - if user wants then can include polyfil from separate repo - but then it's extra request or extra job to bake it into users code.
There is a way to create a copy of String prototype and assign it to new class - OurString and decorate it encapsulated only in module scope. @daurnimator what do you think?
or https://github.com/alexei/sprintf.js/pull/193
