I installed JSLint into VS2010. It works great, except that after it gets to line 50 of the file it is checking, it halts with the message JS Lint: Stopping. (37% Scanned).
When I put the same JS into JSFiddle, and use the JSLint tool there...I get a report that spans the entire file. How can I make the JSLint in Visual Studio scan the entire file?
Does it report a validation error on line 50? Perhaps if you could list the content of line 50, somebody may know what feature it does not like.
JSLint unfortunately stops scanning when it comes across a loop with a variable that wasn't defined outside the loop, e.g.
for (var i=0; i < x; i++)
JSLint gets mighty upset if you declare a variable like shown - I think it is to do with the potentially you have not realising that the variable does not have loop scope.
I had a quick play with JSFiddle's JSLint and I could not get it to report anything as an error, so either this doesn't work or it uses an old JSLint, which doesn't include the feature that causes it to stop in Visual Studio. Does it fail when using http://www.jslint.com/?
Related
I'm an desktop application developer trying to learn the avalanche of technologies for web programming. I decided to focus with Angular(2-4 whatever) because it seemed like the it might be around for more than a year. I'm taking a course that is focusing on TypeScript right now. I'm using Visual Studio Code (1.14.0 - I just updated it) with TypeScript version 2.4.1 (That's what it shows in the lower right corner).
The instructor is showing us how to 'transpile' with command lines (which was another mess I wasted my morning on - see tsc.cmd as opposed to tsc).
The example in question is simply this one line, the first and only line in the Visual Studio Code editor:
let message = 0;
I get the red line of error under the 'message' telling me that:
[ts] Cannot redeclare block-scoped variable 'message'.
It worked for the instructor (on his MAC) but so did the ts compiler command.
If I change it to
let messag = 0;
The error goes away. I can't find where message is a command, statement or global variable in Type Script.
It seems like I'm running the latest of node and type script. I just worry that something is not correctly installed on my machine.
I am still getting use to the idiosyncrasies of VS Code.
My issue was that I put 'archive' copies of my previous code in a subfolder not realizing that these would be loaded as part of the 'assembly'.
Don't simply close the folder! If you are looking at just a single file, the editor will turn off intellisense for typescript.
My solution was to move my archived files out from under the folder AND rename them so their extension was no longer .ts.
Is it a npm project? If not - make it one and use the features of tsconfig.json, where you can exclude files if necessary. Maybe also use GIT? You could create a template repo (with a default configuration) for cloning and then adding specific stuff.
I know that I can type into Chrome or FF the following command:
Object.keys(window);
but this displays DHTMLX stuff and also function names in which I'm not interested in. And it doesn't display variables in functions that have not been executed yet. We have more than 20,000 lines of JavaScript codebase, so I would prefer static code analyis. I found JavsScript Lint. It is a great tool but I don't know how to use it for displaying global vars.
So I'm searching for memory leaks, forgotten var keywords, and so on...
To do [only] what you're asking, I think you're looking for this:
for each (obj in window) {
if (window.hasOwnProperty(obj)) {
console.log(obj);
}
}
I haven't linted that code, which is unlike me, but you get the idea. Try setting something first (var spam = "spam";) and you'll see it reported on your console, and not the cruft you asked about avoiding.
That said, JLRishe is right; JSLint executes JavaScript in your browser without "phoning home", so feel free to run it. There are also many offline tools for JSLinting your code. I use a plugin for Sublime Text, for instance.
If you'd like some simplest-case html/JavaScript code to "wrap" JSLint, I've got an example here. Just download the latest jslint.js file from Crockford's repository into the same directory, and poof, you're linting with a local copy of JSLint.js. Edit: Added code in a new answer here.
Though understand that you're linting locally with that wrapper or when you visit JSLint.com. Honestly, I can say with some confidence, Crockford would rather not see our code. ;^) You download JSLint.js (actually webjslint, a minified compilation of a few files) from JSLint.com, but you execute in the browser.
(Admittedly, you're technically right -- you never know when that site could be compromised, and to be completely on the up and up, you sh/c/ould vet jslint.js each time you grab a fresh copy. It is safer to run locally, but as of this writing, you appear safe to use JSLint.com. Just eyeball your favorite browser's Net tab while running some test, non-proprietary code, and see if any phoning happens. Or unplug your box's network cable!)
Rick's answer to use "use strict"; is another great suggestion.
A great way to catch undeclared variables is to add 'use strict' to your code.
The errors will appear in the console, or you could display them in a try ... catch block:
'use strict';
try {
var i= 15;
u= 25;
} catch(ee) {
alert(ee.message);
}
I found a very good solution to list all the global variables with the jsl command line tool:
Here is the documentation
I just have to put /*jsl:option explicit*/ into each file that I want to check. Then it is enough to run ./jsl -process <someFile> | grep 'undeclared identifier'
It is also possible to use referenceFile that contains some intentional global variables /*jsl:import <referenceFile>*/ so these variables will not be listed.
We use the Closure Compiler to spot syntax errors in JavaScript and window.onerror to spot all other runtime errors. Every file is augmented with "use strict". None of this catches semicolons that were "helpfully" inserted.
I have tried JSLint, but it has pretty specific ideas about how one should code in JavaScript, and so was less useful than I hoped. For example, with JsLint I can no longer use for (var i = ...) style; JsLint gives up as soon as it encounters one of these.
Is there some other static analysis tool for JavaScript that could warn me about semicolon insertion in particular?
There is also JSHint:
http://www.jshint.com/
You can customize what you want it to warn over. It can be run as a standalone checker as part of your build process, or integrated into various editors.
I'd like to set a breakpoint in a "Cart.add" function in the Chrome or Safari JavaScript debuggers. Problem is, this function is defined in a large minified JS file, and doesn't exist on a line by itself.
Some documentation says that the WebKit-based debuggers support "break" or "debug" commands in the debug console, but those don't seem to work in newer versions of the debugger.
Setting a breakpoint on that line of the JS file doesn't work either, since there are lots of functions on that line.
Any suggestions?
In Chrome when you open Scripts tab you can prettify selected file by clicking on { } button ("Pretty print") at the bottom. After that you can find your line and set a breakpoint. The code will remain prettified with breakpoints in place after a page refresh.
The debugger statement is probably what you're looking for.
Evaluating the DebuggerStatement production may allow an implementation to cause a breakpoint when run under a debugger. If a debugger is not present or active this statement has no observable effect.
The production DebuggerStatement : debugger ; is evaluated as follows:
If an implementation defined debugging facility is available and enabled, then
a. Perform an implementation defined debugging action.
b. Let result be an implementation defined Completion value.
Else
a. Let result be (normal, empty, empty).
Return result.
The break statement is for exiting loops and switch statements and has nothing to do with debugging.
The real solution though is to not bugger your code in the first place :)
1) The error message should give you a link to the source code in the
Sources tab. Click on that link to get taken to the transpiled code.
2) Click the "{ }" icon at the bottom of the source code in the
Sources tab to format the transpiled code for easier debugging.
3)Stick a breakpoint at the line that is failing.
4) Reproduce the
problem again. This time, it should break at the breakpoint before
the error occurs.
5) Examine the local variables and call stack to
determine what exactly is going wrong.
For chrome users, you'll want to enable automatic pretty print in the experimental features.
setting your breakpoint should work now.
If you have saved the webpage then beautify your js file using jsbeautifier.org which formats your entire script. Then replace your js content with the beautified version. From here you can debug your JS easily
When I run SquishIt in development mode everything works fine. When I put it into production mode I am getting the 'missing ; before statement' error in Javascript. I've tried removing the offending javascipt files, but the error moves down to the next one.
Any idea's?
One possibility is that you're missing a ; somewhere in your code that's being automatically inserted by the browser. Use jslint to find the offending lines of code.
I also posted this problem on the Squishit google groups. Justin reponded:
This is a known bug that is going to
be fixed in an soon to be released
SquishIt 0.6.1. Essentially the ajax
minifier is compressing the files
separately before we are combining
them into one. This can cause the
issue you are seeing. The fix in the
meantime is to use the WithCompressor
option and switch to something like
the YUI compressor temporarily.the YUI compressor temporarily.
Bundle.JavaScript()
.Add("/Scripts/Frameworks/jquery.js").WithMinifier(JavaScriptMinifiers.Yui)
....