Know Array

Values that evaluate to true
 

'0';
'any string';
[];  // an empty array
{};  // an empty object
1;   // any non-zero number

Values that evaluate to False
 

0;
'';  // an empty string
NaN; // JavaScript's "not-a-number" variable
null;
undefined;  // be careful -- undefined can be redefined! 

sort in Array

var list =[ 39, 108, 21, 55, 18, 9]  list.sort() //[108, 18, 21, 39, 55, 9 ]  var list =["Zebra", "Monkey", "Donkey"]  list.reverse() //["Monkey", "Zebra", "Donkey"]  --------------------------------------------------------- function sortmyway(data_A, data_B) { if ( data_A < data_B ) // data_A come before data_B return -1; if ( data_A > data_B ) // data_A come After data_B return 1; return 0; // data_A == data_B, no change. } var list =[ 39, 108, 21, 55, 18, 9] list.sort(sortmyway) // [9, 18, 21, 39, 55, 108]    ------------------------------ function sortmyway(data_A, data_B) { return ((data_A < data_B) ? -1 : ((data_A > data_B) ? 1 : 0)); } var list =[ 39, 108, 21, 55, 18, 9] list.sort(sortmyway) // [9, 18, 21, 39, 55, 108] --------------------------------------- function sortmyway(data_A, data_B) { return (data_A - data_B); } var list =[ 39, 108, 21, 55, 18, 9] list.sort(sortmyway) //[9, 18, 21, 39, 55, 108] --------------------------------------------------shortest way   function sortmyway(data_A, data_B) { return 0.5 - Math.random(); //random gives us result between 0 and 1 } var list =[ 39, 108, 21, 55, 18, 9] list.sort(sortmyway) //[21, 9, 39, 108, 18, 55]

how to declare arrray

Example 1 – Array Constructor

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// Declare an array (using the array constructor) var arlene1 = new Array(); var arlene2 = new Array("First element", "Second", "Last");

Example 2 – Literal notatoin

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// Declare an array (using literal notation) var arlene1 = []; var arlene2 = ["First element", "Second", "Last"];

Example 3 – Implicit Declaration

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// Create an array from a method's return value var carter = "I-learn-JavaScript"; var arlene3 = carter.split("-");

To avoid script errors, you should get into the habit of initializing an array when you declare it, like so:

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// Declare an empty array using literal notation: var arlene = []; // The variable now contains an array of length zero

check for array : isArray

$(document).ready(function(){
       var x = [];
       var y = [1,2,3];
       var z = 1;
     $("#result").text('Variable x is an array : ' + $.isArray(x));
      $("#result").append('<br/>' + 'Variable y is an array : ' + $.isArray(y) + '<br/>'); 
      $("#result").append('Variable z is an array : ' + $.isArray(z));
    });

Arrays - tut

jQuery(document).ready(function(){

var arr = [ "earth", "mars", "jupiter", "saturn", "venus" ];

var obj = { one:"earth", two:"mars", three:"jupiter", four:"saturn", five:"venus" };

jQuery.each(arr, function(i, val) {

$("#arrData").append(i + " : " + val + "<br/>");

});

jQuery.each(obj, function(i, val) {

$("#objData").append(i + " : " + val + "<br/>");

});

}); 

 

the run and find diffrence in i as yo print this code; an array and object