new Function() with variable parameters

Question

I need to create a function with variable number of parameters using new Function() constructor. Something like this:

args = [\'a\', \'b\'];
bod         


        

Answer 1

There's a few different ways you could write that.

// assign normally
var ab = ['a','b'].join('');
alert(ab);
// assign with anonymous self-evaluating function
var cd = (function(c) {return c.join("");})(['c','d']);
alert(cd);
// assign with function declaration
function efFunc(c){return c.join("");}
var efArray = ['e','f'];
var ef = efFunc(efArray);
alert(ef);
// assign with function by name
var doFunc = function(a,b) {return window[b](a);}
var ghArray = ['g','h'];
var ghFunc = function(c){return c.join("");}
var gh = doFunc(ghArray,'ghFunc');
alert(gh);
// assign with Class and lookup table
var Function_ = function(a,b) {
  this.val = '';
  this.body = b.substr(0,b.indexOf('('));
  this.args = b.substr(b.indexOf('(')+1,b.lastIndexOf(')')-b.indexOf('(')-1);
  switch (this.body) {
    case "return": 
      switch (this.args) {
        case "a + b": this.val = a.join(''); break;
      }
    break;
  }
} 
var args = ['i', 'j'];
var body = 'return(a + b);';
var ij = new Function_(args, body);
alert(ij.val);