How can I add Key/Value pair to Object

var obj = {
    key1: value1,
    key2: value2
};

There are two ways to add new properties to an object

Method 1 – Using dot notation

 obj.key3 = "value3";

Method 2 – Using square bracket notation

 obj["key3"] = "value3";

The first form is used when you know the name of the property. The second form is used when the name of the property is dynamically determined. Like in this example:

var getProperty = function (propertyName) {
    return obj[propertyName];
};

getProperty("key1");
getProperty("key2");
getProperty("key3");

A real JavaScript array can be constructed using either:

The Array literal notation:

var arr = [];

The Array constructor notation:

var arr = new Array();

Simple 2 Dimensional Array

 var grades = [[89, 77, 78],[76, 82, 81],[91, 94, 89]];
 print(grades[2][2]); 

Method 1

var numeric = [
    ['input1','input2'],
    ['input3','input4']
];
numeric[0][0] == 'input1';
numeric[0][1] == 'input2';
numeric[1][0] == 'input3';
numeric[1][1] == 'input4';

Method 2

var obj = {
    'row1' : {
        'key1' : 'input1',
        'key2' : 'inpu2'
    },
    'row2' : {
        'key3' : 'input3',
        'key4' : 'input4'
    }
};
obj.row1.key1 == 'input1';
obj.row1.key2 == 'input2';
obj.row2.key1 == 'input3';
obj.row2.key2 == 'input4';

Method 3

var mixed = {
    'row1' : ['input1', 'inpu2'],
    'row2' : ['input3', 'input4']
};
obj.row1[0] == 'input1';
obj.row1[1] == 'input2';
obj.row2[0] == 'input3';
obj.row2[1] == 'input4';

Creating a Multidimensional Array on Fly

var row= 20;
var column= 10;
var f = new Array();

for (i=0;i<row;i++) {
 f[i]=new Array();
 for (j=0;j<column;j++) {
  f[i][j]=0;
 }
}

Method to create a Javascript Multidimensional Array

Array.matrix = function(numrows, numcols, initial) {
var arr = [];
for (var i = 0; i < numrows; ++i) {
var columns = [];
for (var j = 0; j < numcols; ++j) {
columns[j] = initial;
}
arr[i] = columns;
}
return arr;
}

Sample Test Values

var nums = Array.matrix(5,5,0);
print(nums[1][1]); // displays 0
var names = Array.matrix(3,3,"");
names[1][2] = "Joe";
print(names[1][2]); // display "Joe"