Javascript call function as string, with multiple parameters not using eval()

Question

I am quite new to javascript, but I know you can call a function with it being represented by a string such that:

 var function_to_call = window[values['function']];
 //Where values['function']='functionName'

So far so good, then we have:

 if(typeof function_to_call == 'function'){
       if(values['parameters']!= '')
                function_to_call(values['parameters']);
       else function_to_call();
  };

Of course, this won´t work because the parameters come out as "parameter1, parameter2" all in one string so you end up with

function_to_call("parameter1, parameter2");

rather than

function_to_call(parameter1, parameter2);

any ideas? Appreciate your time!

EXPANDED:

The parameters passed to the function represent the "id" of elements in the page; so the function that is called will be trying to get those elements by doing:

document.getElementById(parameter1);
...some other things...
document.getElementById(parameter2);

You probably need to parse the parameters string into parameter array first and then use function.apply() to call the function. — bigbearzhu
– bigbearzhu, Commented Jun 14, 2013 at 0:34
@bigbearzhu I´ll look into function.apply() since I don´t know what it is. — Chayemor
– Chayemor, Commented Jun 15, 2013 at 8:38

score 3 · Accepted Answer · 2013-06-14 00:41:20Z

3

I assume the parameter names represent global variables as well.

If so, you could split them into an Array, then .map() the Array into a new array of the related globals.

Then use .apply() to invoke the function with the array of arguments.

if (typeof function_to_call == 'function') {
     if(values['parameters']!= '') {
          var args = values['parameters'].split(",")
                                         .map(function(name) {
                                             return window[name.trim()];
                                         });
          function_to_call.apply(window, args);
     } else function_to_call();
}

The .trim() and .map() methods will need a shim for IE8... but this mainly shows how you could do it. As an alternative, you could pass a regex to .split() to take care of any spaces.

var args = values['parameters'].split(/\s*,\s*/)...

edited Jun 14, 2013 at 0:41

answered Jun 14, 2013 at 0:35

user2437417

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9 Comments

Paul S. Over a year ago

' param, param2 '.trim().split(/,\s*/) is ["param", "param2"], saves you a loop. But what happens if you have a param that looks like "\"hello, world\""?

user2437417 Over a year ago

@PaulS.: Yes, but I think OP wants to resolve them to global variables. If not, then yes, the loop isn't needed.

user2437417 Over a year ago

@PaulS.: Those wouldn't be valid variables. They're valid properties when enclosed in a string, but I'm pretty sure OP is after variables here.

Chayemor Over a year ago

@CrazyTrain What exactly does "I assume the parameter names represent global variables as well." mean?I apologize but I am newbie with javascript, and I believe that that phrase is important because your example is not giving me the result I need.

Chayemor Over a year ago

@CrazyTrain I used .apply(), and parsed the string to array with .split(",") , and made sure that the parameters passed employed no spaces and only comma-separation so as to avoid .map() (to trim white spaces). thanks for the help!

|

ARMBouhali · Accepted Answer · 2013-06-14 00:34:18Z

0

 if(typeof function_to_call == 'function'){
   if(values['parameters']!= '')
            setTimeout('function_to_call('.values['parameters'].');');
   else  setTimeout('function_to_call();',0);
  }

answered Jun 14, 2013 at 0:34

ARMBouhali

2982 silver badges12 bronze badges

1 Comment

Paul S. Over a year ago

Using setTimeout like this is an eval.

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