| If we require many variables of same or different types then a problem of remembering names of variables and many functional problems will arise. Concept of array allows us to store different data type data pieces under the same name in an ordered way. It helps in creating many variables. There is no need of remembering their names because they all have the same name but different positions in the array. The count of location in an array starts from 0 not from 1, means the first location is 0th location and 12th is 11th . |
| Declaring an array variable |
| Method 1 |
| var d = new Array (“One”, “Two”, “Three”, “Four”); |
| Understanding the declaration |
| var – is reserve word |
| d – is the name of the array |
| new – is a reserve word , sets that much number of locations in memory as much parameters given with Array( ); |
| Array( ) – is a reserve word , provides the input to new that how much memory locations are to be reserved. |
| “One”, “Two”, “Three”,” Four” – are the values to set in d named array variable as much the count of these variables is that much of locations in memory will be reserved by new (reserve word). |
| Method 2 |
| var sales = new Array (12); |
| Understanding the declaration |
| var – is reserve word |
| sales – is the name of the array |
| new – is a reserve word , sets that much number of locations in memory as much parameters given with Array( ), in this case 12 locations will be occupied; |
| Array( ) – is a reserve word , provides the input to new that how much memory locations are to be reserved. 12 – is the count of locations to be reserved. |
| Assigning values to an array locations |
| Sales[0] = “Rubber”; |
| Sales [1] = 12000; |
| Sales[2] = “Plastic”; |
| Sales [3] = 18000; |
| At 0th position of sales named array the value is “Rubber “ and at 1st position 12000 is stored. So we can place different data types data in the same array. |
| Example 1 |
| <html> <head> </head> <body> <script type=”text/JavaScript”> var d = new Array(“One”,”Two”,”Three”,”Four”); document.write(“Value at 0th position of d is “+d[0]); document.write(“<br>Value at 1st position of d is “+d[1]); document.write(“<br>Value at 2nd position of d is “+d[2]); document.write(“<br>Value at 3rd position of d is “+d[3]); </script > </body> </html> |
| Output is |
| Value at 0th position of d is One Value at 1st position of d is Two Value at 2nd position of d is Three Value at 3rd position of d is Four |
| Example 2 |
| <html> <head> </head> <body> <script type=”text/javascript”> var sales = new Array(12); sales[0]=”Rubber”; sales[1]=12000; sales[2]=”Plastic” sales[3]=18000; document.write(“Value at 0th position of sales is “+sales[0]); document.write(“<br>Value at 1st position of sales is “+sales[1]); </script > </body> </html> |
| Output is |
| Value at 0th position of sales is Rubber Value at 1st position of sales is 12000 |