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Showing posts from 2014

JavaScript: Next Unique ID Function

Unique ID generation is used in JavaScript application in many places. For example giving the unique id to DOM element or may be using it to some data structure for storing in memory, where it can be use latter.

Most of the implementation I see is just defining the integer and increasing it on every call. But it is potentially candidate to integer overflow issue, which can cause errors in many edge case scenario.

var nextUid = (function(){ var idCounter = 0; //integer counter return function (prefix) { //counter increment on every call, and it can run into integer overflow issue var id = ++idCounter; return String(prefix == null ? '' : prefix) + id; } })();

When I was reading through AngularJS source code, found this really good implementation of unique ID generation. Below is the extracted and updated version of the same, so you can use it independently.

/** A consistent way of creating unique IDs in angular. The ID is a sequence of alpha numeri…

JavaScript: Utility function to default function in parameters

Recently I came across a interesting discussion on reddit. And that was about a utility function which will give you flexibility to define default function in parameters.

I found it very interesting, so wrote one for me.

/* in param: defaultArg1, defaultArg2, .... function return : function */ var defaultParams = function(){ var args = arguments, len = args.length, fn = args[--len], defaultArg = []; if(typeof fn !== 'function'){ throw new Error('invalid arguments'); } while(len--){ defaultArg[len] = args[len]; } return function(){ var args = arguments, fnlen = fn.length, params = []; while(fnlen--){ params[fnlen] = args[fnlen] == null ? defaultArg[fnlen] : args[fnlen]; } return fn.apply(this, params); } } //how to use var alert_my_age = defaultParams(21, function(age) { console.log(age); }) alert_my_age() //#=> Alerts 21 alert_my_age(45) //#=> Alerts 45

JavaScript: Light weight wrapper class for window.localStorage

Recently I wrote a small wrapper class around the window.localStorage with useful functionality apart from normal get/set value.

For example Accessors for JSON/Boolean/Number,Event registering for type create/update/remove/clear eventsAPI functionsLS.set(key, value) LS.setJson(key, jsonObject) LS.remove(key) LS.clear() LS.get(key):String LS.getJson(key): JsonObject LS.getNumber(key): Int LS.getBoolean(key):Boolean//Event API LS.on(event, listenerFunction, scope):function//this return function can be used for unregistering from event//different type and listeners callback param events type:'create' listenerFunction callback param: key, value events type:'update' listenerFunction callback param: key, newValue, oldValue events type:'remove' listenerFunction callback param: key events type:'clear' listenerFunction callback param://remove all the registered event for given event type LS.removeAllEventListeners(eventType) Event registering/unregister…