I'm looking for a way to create variables dynamically in javascript
eg
I have a loop
for (i=0;i<15;i++){
}
now I need to create variables dynamically eg var "a"+i for eavh value in the loop. Is this possible and how?
7 Answers
Since you are dealing with numeric, sequential variables — use an array.
var foo = [];
for (var i = 0; i < 15; i++) {
foo[i] = something;
}
Comments
If we presume that you will need several variables related to each iteration ([foo1,bar1], [foo2, bar2]...) then there are two approaches
Use arrays
var foo = [], bar = [];
foo[1] = "foo";
bar[1] = "bar";
Use an object
var myVars = {};
myVars["foo" + 1] = "foo";
myVars["bar" + 1] = "bar";
That last one could also be written as
myVars.bar1 = "bar";
Do not use eval as some has suggested.
1 Comment
Sean Kinsey
@nemesisdesign I didn't say it was evil, just that it doesn't belong in this use case.
eval is only 'evil' if used wrong, so don't listen to everything The Crock says..To fulfill your exact requirement, I know only eval():
eval("varname"+i+" = 'Hello';");
on the other hand, you could consider using an array. Much cleaner: They don't clutter the global namespace, and you can order variables neatly in groups.
arrayname[i] = value;
Comments
It would be unwise to pollute your namespace with such a large number of variables. Use an array instead.
Comments
You can use the evil eval function for this purpose:
for (var i=0; i < 15; i++){
eval( 'var a' + i + ' = "something"' );
}
Comments
window mostly represents the global object on browsers. You can use either that or scope it to your own objects.
var my = {};
for(var i = 0; i < 15; i++) {
my["a" + i] = "value: " + i;
}
console.log(my.a4); // "value: 4"
var array = []; for (i=0;i<15;i++){array[i] = ...}?