Many thanks to everyone that has been working on code for this!
I just wanted to add that I've been looking for exactly the same thing, but in my case it's for managing a cache of processed objects to avoid having to re-parse and process objects from ajax calls that may or may not have been cached by the browser. This is especially useful for objects that require a lot of processing, usually anything that isn't in JSON format, but it can get very costly to keep these things cached in a large project or an app/extension that is left running for a long time.
Anyway, I use it for something something like:
var myCache = {
cache: {},
order: [],
size: 0,
maxSize: 2 * 1024 * 1024, // 2mb
add: function(key, object) {
// Otherwise add new object
var size = this.getObjectSize(object);
if (size > this.maxSize) return; // Can't store this object
var total = this.size + size;
// Check for existing entry, as replacing it will free up space
if (typeof(this.cache[key]) !== 'undefined') {
for (var i = 0; i < this.order.length; ++i) {
var entry = this.order[i];
if (entry.key === key) {
total -= entry.size;
this.order.splice(i, 1);
break;
}
}
}
while (total > this.maxSize) {
var entry = this.order.shift();
delete this.cache[entry.key];
total -= entry.size;
}
this.cache[key] = object;
this.order.push({ size: size, key: key });
this.size = total;
},
get: function(key) {
var value = this.cache[key];
if (typeof(value) !== 'undefined') { // Return this key for longer
for (var i = 0; i < this.order.length; ++i) {
var entry = this.order[i];
if (entry.key === key) {
this.order.splice(i, 1);
this.order.push(entry);
break;
}
}
}
return value;
},
getObjectSize: function(object) {
// Code from above estimating functions
},
};
It's a simplistic example and may have some errors, but it gives the idea, as you can use it to hold onto static objects (contents won't change) with some degree of intelligence. This can significantly cut down on any expensive processing requirements that the object had to be produced in the first place.
