The document provides code examples and explanations for various JavaScript programming techniques. Some examples covered include: 1. Using logical operators and default parameters to handle function arguments concisely. 2. Different methods for converting strings to numbers, setting default object properties, and checking if an object property exists. 3. Techniques for improving loop performance by caching array lengths and merging arrays without creating new objects. 4. Examples of array slicing and truncation, as well as converting array-like objects to arrays. 5. Explanations of equality comparisons, typeof, instanceof, and immediately invoked function expressions.

1. JavaScript smart Hacks
-Nishchit D.

2. //Expert
function Recharge(amount) {
this.payment = amount;
this.hasBalance = !!amount; // True
}
var doRecharge = new Recharge(100);
//Else
function Recharge(amount) {
this.payment = amount;
if(amount) {
this.hasBalance = true;
}
}
var doRecharge = new Recharge(100);
Boolean with !!

3. //Expert
function setAge(age){
return +age;
}
setAge(25) // 25
setAge('ABC') // NaN
//Else
function setAge(age){
return age * 1;
}
String to Number

4. //Expert
function Car(model, price){
this.price = 1000;
this.model = model || 'Bently';
}
//Else
function Car(model, price){
this.price = 1000;
this.model = model? model: 'Bently';
}
Default value

5. //Expert
var length = array.length;
for (var i = 0; i < length; i++) {
console.log(array[i]);
}
OR
for (var i = 0,length = array.length; i < length; i++) {
console.log(array[i]);
}
//Else
for (var i = 0; i < array.length; i++){
console.log(array[i]);
}
// This will consume more memory
// when array is too large
Loop performance

6. //Expert
if('street' in person.address || {}){
console.log(person.address.street)
// A/2 Park Avenue
}
//Else
if(person
&& person.address
&& person.address.street){
console.log(person.address.street)
// A/2 Park Avenue
}
Check object property exists

7. //Expert
success && goForward();
//Else
if(success){
goForward()
}
Short-circuits condition

8. Array Hacks

9. // Expert
var array = [1, 2, 3, 4, 5, 6];
array.slice(-1) // [ 6 ]
array.slice(-2) // [ 5, 6]
//Else
var array = [1, 2, 3, 4, 5, 6];
array.slice(5) // [ 6 ]
array.slice(4) // [ 6 ]
Get Tailing Array

10.
//Expert
// Remove last two
var numbers = [1, 2, 3, 4, 5, 6];
numbers.length = 4; // numbers = [ 1, 2, 3,
4]
//Else
// Remove last two
var numbers = [1, 2, 3, 4, 5, 6];
numbers.splice(4, 2) // remove [ 5, 6 ]
Array Truncation

11. // Expert
var A1 = [1, 2, 3];
var A2 = [4, 5, 6];
A1.push.apply(A1, A2)
// Else
var A1 = [1, 2, 3];
var A2 = [4, 5, 6];
console.log(array1.concat(array2));
// [1,2,3,4,5,6];
// This will consume more memory
// to create new array
// in case with large array merge.
Array Merge

12. // To get pure array from Array like Object
var pureArray = [].slice.call(object)
OR
var pureArray = Array.from(object)
NOTE:
1. NodeList from DOM is array of DOM but it
don’t have all array protoypes.
2. Arguments from functions are array like
object.
var object = Object.create(Array.prototype);
object.push("foo");
object.push("bar"); // [ 'foo', 'bar' ]
object.me = "ND"
console.log(object)
/**
object
Array[2]
0: "foo"
1: "bar"
length: 2
me: "ND"
__proto__: Array[0]
**/
Array like Object

13. Miscellaneous

14. [10] === 10 // is false
[10] == 10 // is true
'10' == 10 // is true
'10' === 10 // is false
[] == 0 // is true
[] === 0 // is false
'' == false // is true but true == "a" is false
'' === false // is false
== vs ===

15. var arr = ["a", "b", "c"];
typeof arr; // return "object"
arr instanceof Array // true
arr.constructor(); //[]
typeof, instanceof & constructor

16. (function(a,b){
var result = a+b;
return result;
})(10,20)
OR
(function(ng, $){
ng.module(‘app’, []);
})(angular, jQuery)
(function(){
// some private code
// that will be executed automatically
})();
pattern
step 1. ()()
step 2. (FN)()
step 3. (FN)(var1, var2, ...)
IIFE- Immediately Invoked Function Expression
OR
Self-Invoked Anonymous Function.

17. function callMe(){
var argArray = Array.prototype.slice.call(arguments);
conosle.log(argArray) // [ 1, 2, 3, 4, 5 ]
}
callMe( 1, 2, 3, 4, 5)
Transform the arguments Object into an Array

18. //Get the max or the min in an array of numbers
var numbers = [ 200, 30, -434, 546, 237, 11 ];
var maxInNumbers = Math.max.apply(Math, numbers);
var minInNumbers = Math.min.apply(Math, numbers);
Thank you !!
Ohh Sorry...
Last thing to mention.