how to execute javascript function when i send its name as string dynamically with out parameters

one simple way

eval("SomeFunction()");

or

var funcName = "SomeFunction";
var func == window[funcName];
func();

dangerous but you could use eval(method_name+"()")

are you talking about ´eval()´??

var foo = "alert('bar')";
eval(foo);

Hope this helps;

function a() { 
   console.log('yeah!'); 
}

var funcName = 'a'; // get function name

this[funcName]();

If the function is global, you should do window[funcName]() in browser.

Using eval is the worst way imaginable. Avoid that at all costs.

You can use window[functionname]() like this:

function myfunction() {
    alert('test');
}

var functionname = 'myfunction';
window[functionname]();

This way you can optionally add arguments as well

Perhaps a safer way is to do something like this (pseudo code only here):

function executer(functionName)
{
  if (functionName === "blammo")
  {
    blammo();
  }
  else if (functionName === "kapow")
  {
    kapow();
  }
  else // unrecognized function name
  {
    // do something.
  }

You might use a switch statement for this (it seems like a better construct):

switch (functionName)
{
  case "blammo":
    blammo();
    break;

  case "kapow":
    kapow();
    break;

  default:
    // unrecognized function name.
}

You can optimize this by creating an array of function names, searching the array for the desired function name, then executing the value in the array.