I'm trying to execute a function using a string containing the functions name.
Several resources I've found suggest something like this:
function runMe(){alert("fail"));
var fnstring = "runMe";
var fn = window[fnstring];
fn();
However, it doesn't work at all for me (JSFiddle demo). I end up with fn as undefined. Am I doing something wrong, or has window behavior changed?
You're getting the Uncaught TypeError: undefined is not a function error because of hoisting. Looking at the first link you provided, there was one key difference between your version and theirs: the conditional.
function runMe(thething) {
alert("the function has successfully run: " + thething);
}
// function we want to run
var fnstring = "runMe";
alert("string: " + fnstring);
// find object
var fn = window[fnstring]("lkjlksdfsdfj");
alert("function: " + fn);
// is object a function?
alert("is function?: " + typeof fn === "function");
fn();
My version, working without errors:
function runMe(thething) {
console.log("the function has successfully run: " + thething);
}
// function we want to run
var fnstring = "runMe";
// find object
var fn = window[fnstring]("lkjlksdfsdfj");
// is object a function?
if (typeof fn === "function") fn();
The reason why your version throws an error is that it is being hoisted into something like this:
function runMe(thething) {
alert("the function has successfully run: " + thething);
}
var fnstring, fn;
fn();
fnstring = "runMe";
fn = window[fnstring]("lkjlksdfsdfj");
So when it's called it isn't a function; it's an undefined variable.
On the other hand, as far as I understand hoisting, my version gets hoisted something like this:
function runMe(thething) {
console.log("the function has successfully run: " + thething);
}
var fnstring, fn;
fnstring = = "runMe";
fn = window[fnstring]("lkjlksdfsdfj");
if (typeof fn === "function") fn();
So that by the time the function is actually called, everything's good to go.
runMefunction defined in a global scope? "using a string containing the functions name" --- any chance to reconsider this "design"? It smells.No wrap - in bodyin the left 2nd dropdown.<script></script>in the body of my dev page, it breaks with error: "Uncaught TypeError: undefined is not a function".