Javascript to parse string with 'function'

Question

I have following string which needs to be parsed using JS.

function () {\n     MyClass.prototype.doSomethingFunction();\n       5-6 lines of coding\n  }

I tried parsing it, trimming whitespaces and newlines but nothing worked for me. Please let me know how can I get function name (doSomethingFunction) from the above string.

How I'm getting this string:

I have a queue where my functions are stored. Later in time my code picks a function from this queue (some logic here) and execute them. It works perfectly ok for me. But I just want to print the name of the function out of it! It's like '(classOBJ.myFunctionsQueue[n])()' is used to execute a function which is stored at nth location in myFunctionsQueue array. Make sense or I'm doing something wrong in here?

Thanks MANN

Can you not populate your queue with the function name as well as a separate property? i.e., ["doSomethingFunction", "function () {\n... "]. — mellamokb
– mellamokb, Commented Oct 11, 2012 at 14:32
MyClass.prototype.doSomethingFunction() is the whole namespace. I just want doSomethingFunction() out of it. Does this make sense? — MANN
– MANN, Commented Oct 11, 2012 at 14:33
Your solution sounds very fragile. What is the bigger picture goal you are aiming for, perhaps there is a better approach overall? — mellamokb
– mellamokb, Commented Oct 11, 2012 at 14:33

Diode · Accepted Answer · 2012-10-11 14:42:04Z

2

Try a reg expression matching like this

var str = "function() {\n MyClass.prototype.doSomethingFunction();\n 5 - 6 lines of coding\n}";

var matches = str.match(/prototype\.(.+?)\(\)/);
if(matches){
    alert(matches[1]);
}

answered Oct 11, 2012 at 14:42

Diode

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2 Comments

MANN Over a year ago

gr8... thats the thing I was looking for. Thanks a lot Diode. BTW using array to store your function is a good design or bad? From the comments above it sounds like I'm doing something evil!!!

Bergi Over a year ago

@MANN: An array seems to be reasonable for a queue, but storing your functions as strings is evil.

Bergi · Accepted Answer · 2012-10-11 14:49:17Z

0

I don't think it's the right approach for your application, but the current problem could be solved by something like

myFunctionString.split("\n").reduce(function(map, line) {
    if (/^\s*[^\s[\]]+\(\);?\s*$/.test(line))
        map.push(line.split(".").pop().replace(/\(\);?\s*$/, ""));
    return map;
}, []);
// returns an array of invoked method names

answered Oct 11, 2012 at 14:49

Bergi

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2 Comments

MANN Over a year ago

what I'm doing : var myObj = new MYClass(); var queueOBJ = new QUEUECLASS(few param); queueOBJ.addTest(myObj.doSomethingFunction); Is this design alright or ... even @bfavaretto thinks its alright. Would you mind telling me what I'm doing wrong here?

Bergi Over a year ago

You can't really rely on some code in a string, it might too easily change to something non-parsable. Also I don't understand your use case entirely, why would you want to get the property name of the first method called inside some function string?

bfavaretto · Accepted Answer · 2012-10-11 14:52:58Z

0

First, if you're executing functions stored as strings, you're probably doing it wrong (using eval or new Function(body)). Couldn't you use an object as the queue, with the function names as keys, and function references (not strings) as values? Like this:

var queue = {
    "funcName" : function() { /* do something */ },
    "otherFunc" : function() { /* do something else */ }
    /* etc. */
};

Then you can print all names an execute all function from a loop, for example:

for(var key in queue) {
    console.log(key); // function name
    queue[key]();     // execute function
}

edited Oct 11, 2012 at 14:52

answered Oct 11, 2012 at 14:47

bfavaretto

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2 Comments

MANN Over a year ago

I doubt that I'm storing my functions as string. Let me tell you what I'm doing : var myObj = new MYClass(); var queueOBJ = new QUEUECLASS(few param); queueOBJ.addTest(myObj.doSomethingFunction); Is this design alright or ...

bfavaretto Over a year ago

That looks fine. You said it was a string and needed parsing, hence my answer.

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