I want to call a function this way
redBall(this);
but I want to dynamically construct from a string. I tried something like this but it's not working.
var color = 'red';
color+'Ball'(this);
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4 Answers
You could do something like this:
var ballFunctions = {
redBall: function(obj) {
alert("Hi, I'm a red ball");
},
blueBall: function(obj) {
alert("Hi, I'm a blue ball");
}
};
color = "red";
ballFunctions[color + "Ball"](this);
color = "blue";
ballFunctions[color + "Ball"](this);
You could also combine this with Jimmy's answer and do:
function ball(color, obj) {
ballFunctions[color + "Ball"](obj);
// Or use the window object if your funcs are in the global namespace like Cameron said
// window[color + "Ball"](obj);
}
color = "red";
ball(color, this);
1 Comment
Matt Greer
and you can do
ballFunctions['myNewFunction'] = function() { ... }Subscript the implicit window object:
window[color + 'Ball'](this)
Your example was attempting to call the string 'Ball' (which doesn't make sense since strings aren't callable), then concatenate the result with color -- not quite what you wanted.
1 Comment
Cameron
@jarn: Well, that error means that 'redBall' is not a function in the global namespace (i.e. on the
window object). Where is it defined? Inside another function? Most importantly, what is this in your context?Dynamically named functions aren't a great practice. What about this?
function Ball(color, object)
{
// do stuff
}
And then call it via: Ball('red', this);
5 Comments
icktoofay
Functions that do everything aren't that great of a practice either.
Jimmy Sawczuk
I would still say dynamic function names are a bad way to implement the logic there. A switch statement with other function calls or perhaps a method like Rfvgyhn (that's hard to type) suggested is going to produce much more maintainable code.
JasonFruit
I really have to agree --- there's no way you have to do something this ugly.
mu is too short
@jarn: JavaScript is not PHP, trying to write PHP in JavaScript will only lead to an ugly mess. Doing this sort of thing is a bad idea so there's no good reason that it should be easy anywhere.
Jimmy Sawczuk
@mu And honestly, doing that in PHP makes me nervous too. Just because it's easy doesn't make it a good practice.
To avoid any modification to your existing code (which I assume is globally scoped) you can use this:
window[color + 'Ball'](this);
1 Comment
JAAulde
You're gonna have to show more code, then, and some which reflects actual context.