Here is the listing of useful prototype functions for String and Array used in JavaScript:
String.format:
This function formats the string. This is equivalent of C# 'string.Format' function.
// This is similar to C# 'string.format' function
String.prototype.format = function() {
var txt = this,
i = arguments.length;
while (i--) {
txt = txt.replace(new RegExp('\\{' + i + '\\}', 'gm'), arguments[i]);
}
return txt;
};
// Usage:
'{0}:{1} {2} to {3}:{4} {5} {6}<br />'.format('07', '00', 'AM', '07', '00', 'PM');
// Output:
07:00 AM to 07:00 PM
String.replaceAll
This function removes matched string with the specified string.
// This is similar to 'string.Replace' function
String.prototype.replaceAll = function(pcFrom, pcTo) {
var i = this.indexOf(pcFrom);
var c = this;
while (i > -1) {
c = c.replace(pcFrom, pcTo);
i = c.indexOf(pcFrom);
}
return c;
}
// Usage:
'This is test. <BR> This is test.'.replaceAll("BR", "br");
// Output:
'This is test. <br> This is test.'
String.prototype.trim
This function trims spaces from left and right side of the string.
// Removes spaces from left and right side of string
String.prototype.trim = function() {
return this.replace(/^\s+|\s+$/g, "");
}
// Usage:
' Testing functionality '.trim();
// Output:
'Testing functionality'
String.prototype.ltrim
This function trims spaces from left side of the string.
// Removes left side spaces from string
String.prototype.ltrim = function() {
return this.replace(/^\s+/, "");
}
// Usage:
' Testing functionality'.ltrim();
// Output:
'Testing functionality'
String.prototype.rtrim
This function trims spaces from right side of the string.
// Removes spaces from right side of the string
String.prototype.rtrim = function() {
return this.replace(/\s+$/, "");
}
// Usage:
'Testing functionality '.rtrim();
// Output:
'Testing functionality'
Array.contains
This function checks whether item exists in array or not.
// Attached "contains" method to array.
Array.prototype.contains = function(obj) {
var i = this.length;
while (i--) {
if (this[i] === obj) {
return true;
}
}
return false;
}
// Usage:
var array = new Array(1, 2, 3, 4, 5);
1. array.contains(2);
2. array.contains(7);
// Output:
1. true
2. false
Array.prototype.remove
This function removes items from the array based on index.
// Attached "remove" method to array.
Array.prototype.remove = function(from, to) {
var rest = this.slice((to || from) + 1 || this.length);
this.length = from < 0 ? this.length + from : from;
return this.push.apply(this, rest);
};
// Usage:
var array = new Array(1, 2, 3, 4, 5);
array.remove(1,2);
// Output:
Array contents: 1,4,5
Array.prototype.getItem
This function gets the object from list of objects based on object id. Here assumed that 'Id' property contains object ID.
// Attached "getItem" method to array.
Array.prototype.getItem = function(id) {
var i = this.length;
while (i--) {
if (this[i]["Id"] === parseInt(id)) {
return this[i];
}
}
return null;
}
// Usage:
var entityList = new Array();
entityList.push({ Id: 1, Name: "Name 1" });
entityList.push({ Id: 2, Name: "Name 2" });
entityList.getItem(1);
// Output:
{ Id: 1, Name: "Name 1" }
Array.prototype.containsId
This function checks whether object with passed ID exists in the list of objects. Here assumed that 'Id' property contains object ID.
// Attached "containsId" method to array.
Array.prototype.containsId = function(id) {
var i = this.length;
while (i--) {
if (this[i]["Id"] === parseInt(id)) {
return true;
}
}
return false;
}
// Usage:
var entityList = new Array();
entityList.push({ Id: 1, Name: "Name 1" });
entityList.push({ Id: 2, Name: "Name 2" });
1. entityList.containsId(1);
2. entityList.containsId(7);
// Output:
1. true
2. false
Array.prototype.removeItem
This function removes the object from list of objects based on object id. Here assumed that 'Id' property contains object ID.
// Attached "removeItem" method to array.
Array.prototype.removeItem = function(id) {
var i = this.length;
while (i--) {
if (this[i]["Id"] === parseInt(id)) {
this.splice(i, 1);
return;
}
}
}
// Usage:
var entityList = new Array();
entityList.push({ Id: 1, Name: "Name 1" });
entityList.push({ Id: 2, Name: "Name 2" });
entityList.removeItem(1);
// Output:
'entityList' contents: { Id: 2, Name: "Name 2" }
Array.prototype.addItem
This function adds the object to list of objects.
// Attached "addItem" method to array.
Array.prototype.addItem = function(id) {
// Form an object if you want for passed 'id'
var obj = new obj();
this.push(obj);
}
OR
// Attached "addItem" method to array.
Array.prototype.addItem = function(obj) {
this.push(obj);
}
// Usage:
var entityList = new Array();
entityList.push({ Id: 1, Name: "Name 1" });
entityList.push({ Id: 2, Name: "Name 2" });
entityList.addItem({ Id: 3, Name: "Name 3" });
// Output:
'entityList' contents: { Id: 1, Name: "Name 1" }, { Id: 2, Name: "Name 2" }, { Id: 3, Name: "Name 3" }
Array.prototype.updateItem
This function updates the object property from list of objects based on object id. Here assumed that 'Id' property contains object ID.
// Attached "updateItem" method to array.
Array.prototype.updateItem = function(id, field, value) {
var i = this.length;
while (i--) {
if (this[i]["Id"] === parseInt(id)) {
this[i][field] = value;
}
}
}
// Usage:
var entityList = new Array();
entityList.push({ Id: 1, Name: "Name 1" });
entityList.push({ Id: 2, Name: "Name 2" });
entityList.updateItem(1, "Name", "Name 11");
alert(entityList[0].Name);
// Output:
Alert result: "Name 11";
All these items from listing are not written by me 
(I just copied few of them by googling). Thanks to community who wrote some of them.
Happy programming!
.