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Fix: Unused recursive function expressions should be flagged (fixes #… #11032

merged 1 commit into from Nov 9, 2018


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commented Oct 30, 2018

What is the purpose of this pull request? (put an "X" next to item)

[ ] Documentation update
[x] Bug fix (template)
[ ] New rule (template)
[ ] Changes an existing rule (template)
[ ] Add autofixing to a rule
[ ] Add a CLI option
[ ] Add something to the core
[ ] Other, please explain:


What changes did you make? (Give an overview)

Added getFunctionDefinitions to get a list of function definitions for a passed variable, added checks for FunctionExpression and ArrowFunctionExpression, see corresponding unit tests.


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commented Oct 30, 2018

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All committers have signed the CLA.

@eslint eslint bot added the triage label Oct 30, 2018

@sergei-startsev sergei-startsev force-pushed the sergei-startsev:issue10982 branch from 03e2981 to 8096f33 Oct 30, 2018

* @returns {ASTNode[]} Function nodes.
* @private
function getFunctionDefinitions(variable) {

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aliaksandr-yermalayeu Oct 30, 2018

I would suggest 'map' usage instead of 'forEach':

const getFunctionDefinitions = variable => => {
        const { type, node } = def;
        // FunctionDeclarations
        if (type === "FunctionName") {
            return node;
        // FunctionExpressions
        if (type === "Variable" && node.init &&
            (node.init.type === "FunctionExpression" || node.init.type === "ArrowFunctionExpression")) {
            return node.init;
    }).filter(a => a);

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sergei-startsev Oct 30, 2018

Author Contributor

I wouldn't like to use both map and filter here, but let's wait maintainers' feedback

@platinumazure platinumazure added bug rule and removed triage labels Oct 30, 2018

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Hi @sergei-startsev, thanks for the PR!

I don't have strong feelings on forEach vs map/filter (although I'll say I have no problem with map then filter).

Are there any test cases that show a recursive function not triggering this rule if it's initially called from the outside? Something like: function a() { a(); } a(); If any tests like that are missing, please add them. Thanks!

@sergei-startsev sergei-startsev force-pushed the sergei-startsev:issue10982 branch from 8096f33 to 2f1bfed Oct 30, 2018


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commented Oct 30, 2018

@platinumazure Thanks for the review, I've added a few more tests to be sure that the rule doesn't have false positive issues.


nzakas approved these changes Nov 9, 2018


btmills approved these changes Nov 9, 2018

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LGTM, thanks @sergei-startsev!

@nzakas nzakas merged commit 9436712 into eslint:master Nov 9, 2018

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