How do I optimize this (node.js)?

The loop seems unnecessary but I don't know how to get rid of it.


var a = [
            "Start ",
            function(){return "middle "},
            "end"
        ],
    c = "";
for(var i = 0; i < a.length; i++){
    var d = typeof a[i] === 'function' ? a[i]() : a[i];
    c = c.concat(d);
}
console.log(c);

var a is generated once at runtime from an array of strings and another array of functions. The functions obviously return dynamic content so doing something like this var a = a[0]+a[1]()+a[2]; by loop once at runtime is not an option since I'd be saving the result of the function and not the function itself.

I've seen some code where a tailor-made function function(){return a[0]+a[1]()+a[2];} is created at runtime that returns the strings and functions() correctly but I don't know how to achieve something like that. In the example I saw the JavaScript source stored in a "string" and editted via String methods and then eval() evaluated. I don't even know if it's worth it in that case.

Thoughts? Help?!

JavaScript maps are shit. The only reason for you to use them is to beautify your code. But on average they are slower than a simply for loop like OP's.

I'd speculate that it's because of the extra function call.

>>21

I'm not sure if it would apply to >>8 and >>10, but it could also be the allocation of intermediate arrays that can other wise be avoided.

like the difference between:

array.map(f).map(g).map(h)

and

array.map(compose(f,g,h))