Improve warning message information

[ShuvoHabib]

It says "Vue Warn : Handler for event click is undefined"
It has got an error on somewhere related to event click, I've hundreds of component with click events. In which component/file will I get the error?

[rajibahmed]

This filed issue requires more information. Are you using vue 2 or vue 1.
Is it a bug or a suggestion ? if bug then a reproducible link on jsfiddle.
If any of your component don't have a handler function, this can not be a vue issue.

//Best

[ShuvoHabib]

I'm using Vue 2. It's not a bug. It's an error message that's of no use. Well , Vue can take this as a suggestion to improve the error message style and make it specific. So that, by any mistake if any developer makes a mistake s/he can fix it in little time by knowing exactly where the mistake is. In comparison to React JS, they show the component name along with line number and of course the error too.

All I wish, there error messege to be specific.

[itsMapleLeaf]

There are lots of messages in Vue that don't really say much. Vue's safety checks seem to be lacking, unfortunately.

[rajibahmed]

I guess if vue can add bit more info to its warnings -

component name
component type
or
can make the warning message configurable for development env.

[yyx990803]

We do try to provide component information whenever we can, this one maybe an oversight.

@just-nobody please provide specific examples of which messages are lacking so that we can improve - just complaining achieves nothing.

[itsMapleLeaf]

I wasn't really complaining; I figured that was kind of just something people already knew. I've run into plenty of small edge cases in the past that gave an odd, nondescript message of the actual issue, but instead rooted deep in the source, and some other issues didn't emit an error, and instead caused some weird rendering bug. Some were easier to track down than others so I didn't bother reporting them since I figured it was just me being stupid, but one in particular I actually created a pull request for because it took so long for me to figure out what was wrong.

I imagine the lot of them are fixed now that 2.0.1 is out, but my bad for staying silent, I guess. A message to readers: if you think it's a bug, report it, even if it might end up not being a bug.

[ShuvoHabib]

@yyx990803 Even, Providing the name key of a component doesn't help much. Thanks for stopping by and adding this issue as an improvement.

[rajibahmed]

:) thanks Evan

[MattCCC]

Hi, I have noticed recently that lack of line numbers makes things really hard to debug especially if component is big. I have a component with couple thousands of lines. I received a warning
"[Vue warn]: Error in render function: "TypeError: _vm.values[item.name] is undefined""

There is a component name, but no line number in my Firefox console. For this kind of cases it would be really useful to have a specified line number. Of course I can split component to several smaller ones or just dig through all these lines with editor's search but that's not the point.

Please consider adding line numbers in next versions. Thank you.

[ameoba32]

+1 Please add line numbers.

I got next message,

vue.js:577 [Vue warn]: Error in render: "TypeError: Cannot read property 'length' of undefined"
(found in )

I know why it fails, on this construct " variable.length" if variable == null. Problem is that I have many of ".length" constructs, data is coming from external service.

[AnthonyCouval]

Same for me @ameoba32
I have "Cannot read property 'length' of undefined" and I don't find where is the problem. It's a big webapp so it's hard.
I suppose that I found file in cause but I don't know where error is exactly.
Should I erraze line by line for find the line broken ? xD