Nested Loops

Here's the script:

var height = prompt("How high do you want the grid? (1 - 10 is good)", "10");
var width = prompt("How wide do you want the grid? (1 - 10 is good)", "10");
var aLine;

var newWindow = window.open("grid.htm", "looper", "width=400,height=400");

newWindow.document.write("<H1>A Grid</H1>");

for (i = 0; i < height; i++) {

aLine = "";

for (j = 0; j < width; j++) {

aLine += "x";

}

newWindow.document.write(aLine + "<BR>");

}

After asking for height and width, opening a new window, and writing a header to it, we go into a for loop. The first for loop sets aLine = "". Try doing the example without this line and see what happens.

After initializing aLine, the script goes into another for loop to build a line of x's as wide as required and prints it out to the new window. This happens height times.