Cycle.js: A JavaScript implementation of Rail's text helper
Posted August 3rd, 2008; 0 comments.
On a recent project I had to zebra-stripe a table on the client side in JavaScript, and set out to write to port Rail’s cycle text helper to JavaScript. I rewrote it a couple weeks later using what Douglas Crockford calls the module pattern.
var Cycle = function(){
var cycles, that, thru, reset;
cycles = {};
that = {};
thru = function(){
var values, i, cycle, options, name, nextValue;
values = Array.prototype.slice.call(arguments);
options = typeof(values.slice(-1)[0]) === 'object' ? values.pop() : {};
name = options['name'] || 'default';
if(!cycles[name]) {
cycles[name] = {
values: values,
index: 0
};
};
cycle = cycles[name];
nextValue = cycle.values[cycle.index];
cycle.index = (cycle.index === cycle.values.length -1) ? 0 : (cycle.index +1);
return nextValue;
};
that.thru = thru;
reset = function(name) {
if(cycles[name]) {
cycles[name].index = 0;
}
};
that.reset = reset;
return that;
}();
Usage is fairly simple:
>>> Cycle.thru('one', 'two');
"one"
>>> Cycle.thru('one', 'two');
"two"
>>> Cycle.thru('one', 'two');
"one"
Passing an object literal containing a name property allows for reset functionality:
>>> Cycle.thru('one', 'two', 'three', {name: 'numbers'});
"one"
>>> Cycle.thru('one', 'two', 'three', {name: 'numbers'});
"two"
>>> Cycle.reset('numbers');
>>> Cycle.thru('one', 'two', 'three', {name: 'numbers'});
"one"
I’ve started a GitHub repository for this and other small Javascript utility functions.