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@netpoetica netpoetica/Clevar.js
Last active Dec 21, 2015

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Clevar constructs an accessor function that retains its own History Store and keeps the value absolutely private. Neat utility for tracking history of a variable over time.
var Clevar = function(value){
// Constructs an accessor function that retains its own History Store.
var _this = this;
var _history = []; // Indexable history (newest to oldest)
// Define static objects, only the first time Clevar is run.
Clevar.Record = Clevar.Record || function(value){
this.created = new Date();
this.value = value;
};
Clevar.Record.prototype.getFormatted = Clevar.Record.prototype.getFormatted || function(next){
return 'Value was ' + this.value + ', created at ' + this.created.toUTCString() + (next ? ' and changed at ' + next.created.toUTCString() : '');
};
var Record = Clevar.Record; // Reference to static object - reduce scope lookup.
var _current = value ? new Record(value) : new Record(null); // Current value
return function(value, index/* Only for use with exploring history */){
// Value should be able to be 0 or null and go on record.
if(value !== undefined){ // SET
// User is requesting history of Clevar instance. If index provided does not exist, returns all records for user to sort through.
if(value === '__history'){ return (index !== undefined && typeof _history[index] === 'object') ? _history[index].getFormatted(typeof _history[index + 1] === 'object' ? _history[index + 1] : null) : _history; }
// Need to perform a deep clone on objects, otherwise passed by reference. Save for a more clevar solution.
// If you have jQuery, prototype, or anything with an extend/deep clone function, this would be the place to use it.
if(_current.value instanceof Object && typeof $.extend === 'function'){
_history.push($.extend({}, _current));
} else {
// Otherwise, no deep clone.
_history.push(_current);
}
// Set new current value.
_current = new Record(value);
} else { // GET
return _current.value;
}
}
};
/*
USAGE:
// Declare.
var a = new Clevar('hello');
// Set.
a('world');
a(20);
// Get.
a(); // -> world
// Full history.
a('__history'); // -> [Record, Record, Record]
// History by index.
a('__history', 2); // -> Informative string.
*/
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