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POExtracting nested function names from a JavaScript function
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copied!<p>Given a function, I'm trying to find out the names of the nested functions in it (only one level deep).</p> <p>A simple regex against <code>toString()</code> worked until I started using functions with comments in them. It turns out that some browsers store parts of the raw source while others reconstruct the source from what's compiled; The output of <code>toString()</code> may contain the original code comments in some browsers. As an aside, here are my findings:</p> <h2>Test subject</h2> <pre><code>function/*post-keyword*/fn/*post-name*/()/*post-parens*/{ /*inside*/ } document.write(fn.toString()); </code></pre> <h2>Results</h2> <pre> Browser post-keyword post-name post-parens inside ----------- ------------ --------- ----------- -------- Firefox No No No No Safari No No No No Chrome No No Yes Yes IE Yes Yes Yes Yes Opera Yes Yes Yes Yes </pre> <p>I'm looking for a cross-browser way of extracting the nested function names from a given function. The solution should be able to extract "fn1" and "fn2" out of the following function:</p> <pre><code>function someFn() { /** * Some comment */ function fn1() { alert("/*This is not a comment, it's a string literal*/"); } function // keyword fn2 // name (x, y) // arguments { /* body */ } var f = function () { // anonymous, ignore }; } </code></pre> <p>The solution doesn't have to be pure regex.</p> <p><strong>Update:</strong> You can assume that we're always dealing with valid, properly nested code with all string literals, comments and blocks terminated properly. This is because I'm parsing a function that has already been compiled as a valid function.</p> <p><strong>Update2:</strong> If you're wondering about the motivation behind this: I'm working on a new JavaScript unit testing framework that's called <a href="http://jsunity.com" rel="nofollow noreferrer">jsUnity</a>. There are several different formats in which you can write tests & test suites. One of them is a function:</p> <pre><code>function myTests() { function setUp() { } function tearDown() { } function testSomething() { } function testSomethingElse() { } } </code></pre> <p>Since the functions are hidden inside a closure, there's no way for me invoke them from outside the function. I therefore convert the outer function to a string, extract the function names, append a "now run the given inner function" statement at the bottom and recompile it as a function with new <code>Function()</code>. If the test function have comments in them, it gets tricky to extract the function names and to avoid false positives. Hence I'm soliciting the help of the SO community...</p> <p><strong>Update3:</strong> I've come up with <a href="https://stackoverflow.com/questions/517411/extracting-nested-function-names-from-a-javascript-function/546984#546984">a new solution</a> that doesn't require a lot of semantic fiddling with code. I use the original source itself to probe for first-level functions.</p>

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