An in depth discussion of JavaScript Arrays - Working with two dimensional arrays: discussion

Within the code in the previous section, I mainly created a simple button (which is identified as “ButtonShow”). The button is defined with an “onclick” event which calls a JavaScript function “ButtonShow_onclick”, which is defined as follows:

function ButtonShow_onclick() {
Show();
}

The above function simply calls another JavaScript function named “Show.” The function “Show” is defined as follows:

function Show()
{
var ITArray = new Array(2300, 3105, 2909, 4800);
var ProductionArray = new Array(1800, 1940, 2470, 4350);
var ResearchArray = new Array(900, 1200, 1923, 3810);
var salaryArray = new Array(ITArray, ProductionArray, ResearchArray);

for (var i = 0; i < salaryArray.length; i++) {
for (var j = 0; j < salaryArray[i].length; j++) {
document.write(salaryArray[i][j] + "\t");
}
document.write("
")
}
}

Before starting this discussion, we need to understand what we are creating (in memory) from the above code. Let me provide you a logical view for the array (“salaryArray”) in the above code. Consider the following figure (Fig 01):

Just consider the above figure as a small part of memory identified by “salaryArray.” All the black numbers correspond to values. All the reds are access notations (the positions) for the values given in black. Every access notation is a combination of a row index (in blue) and a column index (in green).

We are trying to create three single dimensional arrays as part of the main array, and thus we describe the main array as a “two dimensional” array (which is very similar to the concept of matrices in mathematics).

According to the above code, the three single dimensional arrays (or rows) are “ITArray”, “ProductionArray” and “ResearchArray. All of them have their own values (but the number of values in all of them is generally the same). We created a main array named “salaryArray” which contains the three arrays in the form of a list (thus forming a table type of view).

Finally, we retrieve and display all the values in the “salaryArray” with the following nested loop:

for (var i = 0; i < salaryArray.length; i++) {
for (var j = 0; j < salaryArray[i].length; j++) {
document.write(salaryArray[i][j] + "\t");
}
document.write("
")
}

With the above code fragment, the variable “i” corresponds to the “row index” and the variable “j” corresponds to the “column index.”