Javascript - Higher Order Function

HigherOrderFunction

<!DOCTYPE html>
<html>
<body>
<script language="javascript" type="text/javascript">
<!--
// Define two simple functions
var add_2 = function(x) {
    return x + 2;
};
var double = function(x) {
    return 2 * x;
};

var sqrt = function(x){
  return x * x;
}

// map is cool function that accepts 2 arguments:
//  func    the function to call
//  list    a array of values to call func on
var map = function(func, list) {
    var output=[];              // output list
    for(idx in list) {
        output.push( func(list[idx]) );
    }
    return output;
}


var buildProcessor = function(func) {
    var process_func = function(list) {
        return map(func, list);
    }
    return process_func;
}
// calling buildProcessor returns a functoin which is called with a list input


// using buildProcessor we could generate the add_2 and double list processors as follows:
process_add_2 = buildProcessor(add_2);
process_double = buildProcessor(double);

 // => [7, 8, 9]
//process_double([5,6,7]) // => [10, 12, 14]

document.body.innerHTML = buildProcessor(sqrt)([5,6,7]);
//-->
</script>
</body>
</html>