How to create an inspection for JavaScript?

Answered

Created July 26, 2022 17:27

I want to write an inspections which forbids usage of jQuery selectors: `$('selector')`.

Which language(s) should I use? jQuery/JavaScript can occur in JSP, HTML, JS, Typescript files. But plugin.xml does not have any defined type for JS or typescript.

At the moment I left out the language attribute, but then my inspection is called in JSPs 3 times (for JSP_FILE, JSP_TEMPLATE, JSP_JAVA_DECLARATIONS) and therefore I have 3 registered problems.

<localInspection enabledByDefault="true" level="ERROR"
                 displayName="Do not use jQuery selectors"
                 implementationClass="net.chrono24.intellij.codequality.inspection.text.NoJQuerySelectorInspection"
/>

class NoJQuerySelectorInspection : LocalInspectionTool() {
    companion object {
        val JQ_PATTERN: Pattern = Pattern.compile("\\$\\([^)]+\\)")
    }
    override fun checkFile(file: PsiFile, manager: InspectionManager, isOnTheFly: Boolean): Array<ProblemDescriptor>? {
        val matcher = JQ_PATTERN.matcher(file.text)

        if (matcher.find()) {
            val problemDescriptor = manager.createProblemDescriptor(
                file, TextRange(matcher.start(), matcher.end()), "Do not use jQuery: #ref", GENERIC_ERROR_OR_WARNING, true
            )

            return arrayOf(problemDescriptor)
        }

        return null
    }

}

4 comments

Karol Lewandowski

Created July 27, 2022 09:19

Hi Martin,

You should register it in the language of the inspected element. I suggest inspecting the PSI tree with https://plugins.jetbrains.com/docs/intellij/explore-api.html#31-use-internal-mode-and-psiviewer to understand how the code structure is built and what are the languages of specific elements.

Also, it seems you need to implement LocalInspectionTool.buildVisitor(ProblemsHolder, boolean) method, not checkFile().

Martin Hofmann-Sobik

Created July 29, 2022 17:31

Hi Karol,

thanks that got me a step closer.

My first error was what I missed the JavaScript plugin, which I now have added.

platformPlugins =com.intellij.jsp, JavaScript

Then I switched from checkFile() to buildVisitor()

override fun buildVisitor(holder: ProblemsHolder, isOnTheFly: Boolean): PsiElementVisitor {
    return object : PsiElementVisitor() {
        override fun visitElement(element: PsiElement) {
            if (element.text == "$") {
                println(element.javaClass)
            }

This code and the suggested PSI viewer showed me that I should care about com.intellij.lang.javascript.psi.impl.JSReferenceExpression.

But if I try that

if (element is JSReferenceExpression)

I get an java.lang.NoClassDefFoundError: com/intellij/lang/javascript/psi/JSReferenceExpression

I also tried to use a JSElementVisitor which would be much nicer, with the same result: java.lang.NoClassDefFoundError: com/intellij/lang/javascript/psi/JSElementVisitor

override fun buildVisitor(holder: ProblemsHolder, isOnTheFly: Boolean): PsiElementVisitor {
    return object : JSElementVisitor() {
        override fun visitJSReferenceExpression(node: JSReferenceExpression?) {

So how can I add the JS classes available in the plugin classpath?

Karol Lewandowski

Created August 01, 2022 11:41

Hi,

Gradle dependency on the JavaScript plugin is just one part of defining dependency.

You should also define dependency in plugin.xml file according to the docs:
https://plugins.jetbrains.com/docs/intellij/plugin-dependencies.html#3-dependency-declaration-in-pluginxml

Martin Hofmann-Sobik

Created August 01, 2022 18:11

Thanks Karol for your help, that was the missing part. Now everything works properly.

(I thought, that the dependencies would be generated by the patchPluginXml based on the platformPlugins attribute.)

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