jquery-lazylist is a lazy list built on jQuery Deferred.
This is useful to implement counter, fibonacci function with memoization, Ajax pager, and so on.
var counter = new $.LazyList(function(prev) {
var d = $.Deferred();
if (prev) {
prev.promise().done(function(i) {
if (i < 10) {
d.resolve(i+1);
} else {
d.reject();
}
});
} else {
d.resolve(0);
}
return d;
});
for (var i = 0; i <= 13; i++) {
counter.promise().done(function(j) {
console.log(j);
}).fail(function() {
console.log('failed');
});
counter = counter.next();
}0
1
2
3
4
5
6
7
8
9
10
failed
var fib = new $.LazyList(function(prev) {
console.log('generate');
var dfd = $.Deferred();
if (prev && prev.prev()) {
prev.prev().promise().done(function(a) {
prev.promise().done(function(b) {
console.log(a + ' + ' + b + ' = ' + (a+b));
dfd.resolve(a + b);
});
});
} else if (prev) {
dfd.resolve(1);
} else {
dfd.resolve(0);
}
return dfd;
});
for (var i = 0; i <= 10; i++) with({i: i}) {
fib.promise().done(function(v) {
console.log('fib(' + i + ') = ' + v);
});
fib = fib.next();
}
// re-culculate from 0
fib = fib.root();
for (var i = 0; i <= 10; i++) with({i: i}) {
fib.promise().done(function(v) {
console.log('fib(' + i + ') = ' + v);
});
fib = fib.next();
}generate
fib(0) = 0
generate
fib(1) = 1
generate
0 + 1 = 1
fib(2) = 1
generate
1 + 1 = 2
fib(3) = 2
generate
1 + 2 = 3
fib(4) = 3
generate
2 + 3 = 5
fib(5) = 5
generate
3 + 5 = 8
fib(6) = 8
generate
5 + 8 = 13
fib(7) = 13
generate
8 + 13 = 21
fib(8) = 21
generate
13 + 21 = 34
fib(9) = 34
generate
21 + 34 = 55
fib(10) = 55
fib(0) = 0
fib(1) = 1
fib(2) = 1
fib(3) = 2
fib(4) = 3
fib(5) = 5
fib(6) = 8
fib(7) = 13
fib(8) = 21
fib(9) = 34
fib(10) = 55
var pager = new $.LazyList(function(prev) {
console.log('generate');
var dfd = $.Deferred();
var data = {};
var get = function() {
$.ajax({
url: '/some/api',
data: data,
}).done(function(res){
dfd.resolve(res);
}).fail(function(error) {
dfd.reject(error);
});
};
if (prev) {
prev.promise().done(function(res) {
data.until = res.max_id;
get();
});
} else {
get();
}
return dfd;
});// get first page
pager.resolve().done(function(page1) {
console.log(page1);
});
// get first page(cached)
pager.resolve().done(function(page1) {
console.log(page1);
});
// get fifth page
pager.next().next().next().next().resolve().done(function(page5) {
console.log(page5);
});