Check JavaScript for Unexpected Assignments

Question

I have some JavaScript that I want to check to make sure I have no occurrences of using the assignment operator (=) as opposed to the equality operator (==). I've looked at JShint, JSLint, and the Google Closure Compiler. Unfortunately, no matter how I set the previous two tools, I get mounds of junk "errors" about all kinds of nit-picky little things, and the Google Closure Compiler does not detect this very common error.

Are there any tools I may use as an alternative to the three above? Really, I just want to check for this one error. I don't care about anything else.

The only other option ignoring the ones you've mentioned would be to use some form of regexp to look for it, good luck though. I would just use jshint or jslint and fix the rest of the "junk errors" while you're there. — user400654
– user400654, Commented Jan 29, 2015 at 20:27
You could also use your favorite editor to search for = and look at each occurrence manually. — user400654
– user400654, Commented Jan 29, 2015 at 20:28
Eek... I was hoping to avoid that... the project has over 12,000 lines. — Joshua Dannemann
– Joshua Dannemann, Commented Jan 29, 2015 at 20:34
Ouch. bet ya wish the project started out using jslint or similar from the beginning. — user400654
– user400654, Commented Jan 29, 2015 at 20:34
Best bet would be to use jslint or jshint and turn off as many of the optional checks as possible to reduce the amount of errors it catches — user400654
– user400654, Commented Jan 29, 2015 at 20:35

tlehman · Accepted Answer · 2015-01-30 18:04:13Z

1

You can do that with grasp, it is similar to grep, but it searches Javascript abstract syntax trees.

For example, if you checkout the keybase node-client, and then run:

 grasp -r 'if.test[op==]'

It will match all the lines in .js files that contain if-statements that have assignment int their test, here's a screenshot:

enter image description here

edited Jan 30, 2015 at 18:04

answered Jan 29, 2015 at 20:47

tlehman

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6 Comments

ruffin Over a year ago

Can you give a quick example call for this issue?

Joshua Dannemann Over a year ago

@ruffin, I am not entirely sure what you mean. I just want a tool that can scour all the lines of code I have to detect something like this: function test(x){ if(x=10){ //do something } }

Joshua Dannemann Over a year ago

@Tobi Thanks! I am definitely going to install that tool for use in the future. In the meantime, I ran all the code through various formatting applications so that the code style became uniform and I could search using a simple regular expression. In my case, I used UltraEdit to do so. Given there doesn't appear to be a tool that does exactly what I need, I think I just might make an open source program based on JSLint that looks for specific errors. I think that could help a lot of people.

tlehman Over a year ago

@JoshuaDannemann This: grasp -r 'if.test[right.value=0]' app/assets/javascripts will match all if statements with the right value as 0. I can come up with an example for assignment.

ruffin Over a year ago

@JoshuaDannemann Was a question for Tobi. Was trying to grok grasp usage, which he provided -- just looking for one that'd answer your question exactly. That's an interesting, and useful, tool. Edit: Ah, his latest edit is money. Sorry I can't upvote twice. That's neat.

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