Hi all

I’m working my way through the “JavaScript & AJAX for Dummies” book and I’ve created what should be a simple script for a 2-dimensional array, but I can’t get it working and have no idea what the problem is.

Hopefully someone can help fix it? Here’s what I’ve got:

<script type=“text/javascript”>
	cityName = new Array(“Indianapolis”,“New York”,“Tokyo”,“London”);
	distance = new Array(
		new Array(0,648,6476,4000),
		new array(648,0,6760,3470),
		new array(6476,6760,0,5956),
		new array(4000,3470,5956,0)
	);


	function GetCity() {
		var theCity = “”;
		var cityMenu = “Please choose a city by typing in a number: \n\n”;
		cityMenu += “0) Indianapolis\n”;
		cityMenu += “1) New York\n”;
		cityMenu += “2) Tokyo\n”;
		cityMenu += “3) London\n”;

		theCity = prompt(cityMenu);
		return(theCity);
	}

	function main() {
		var output = “”;
		var from = GetCity();
		var to = GetCity();
		var result = distance;
		output = “The distance from “ + cityName;
		output += “ to “ + cityName;
		output += “ is “ + result + “ miles.”;
		alert (output);
	}

	main();

	
</script>

I don’t know java

whats it doing

whats it not doing

wookiemeister said:

I don’t know java

whats it doing

whats it not doing

It isn’t java. It is javascript.

wookiemeister said:

I don’t know java

whats it doing

whats it not doing

When I run the script in a browser, it doesn’t do anything. No messages, no alerts, nothing. Just a blank page.

JTQ said:

wookiemeister said:

I don’t know java

whats it doing

whats it not doing

When I run the script in a browser, it doesn’t do anything. No messages, no alerts, nothing. Just a blank page.

what should it do when its running properly?

var items = ,,];
alert(items); // 1

new array(4000,3470,5956,0)

have you missed a comma here?

wookiemeister said:

JTQ said:

wookiemeister said:

I don’t know java

whats it doing

whats it not doing

When I run the script in a browser, it doesn’t do anything. No messages, no alerts, nothing. Just a blank page.

what should it do when its running properly?

Ask for a city name via a number ( 0 – 3), then ask for another city name via a number (0 – 3), it then returns the distance between the two cities.

sibeen said:

wookiemeister said:

what should it do when its running properly?

Ask for a city name via a number ( 0 – 3), then ask for another city name via a number (0 – 3), it then returns the distance between the two cities.

• nods *

I would write the main programme first up top and put the programmes it uses at the bottom

psychological order for me

var items = ,,];

alert(items);

And the alert is reading from it,

To add things to it you would say items = “Label” ; items = “Value”;

If you want to do all the labels then all the values do..

for(var i = 0 ; i < labelssize; i ++)
{ items = labelhere;
}

for(var i = 0 ; i < labelssize; i ++)
{ items = valuehere;
}

assuming that its not a syntax error eg a missing semi colon, not naming a variable properly

you might want to look at the logic of the programming, maybe you’ve put the horse before the cart in part of the programme?

roughbarked said:

var items = ,,];

alert(items);

And the alert is reading from it,

To add things to it you would say items = “Label” ; items = “Value”;

If you want to do all the labels then all the values do..

for(var i = 0 ; i < labelssize; i ++)
{ items = labelhere;
}

for(var i = 0 ; i < labelssize; i ++)
{ items = valuehere;
}

I’m thinking but not sure how to update my coding to include your suggestion.

JTQ said:

Hi all

I’m working my way through the “JavaScript & AJAX for Dummies” book and I’ve created what should be a simple script for a 2-dimensional array, but I can’t get it working and have no idea what the problem is.

Hopefully someone can help fix it? Here’s what I’ve got:

<script type=“text/javascript”>
	cityName = new Array(“Indianapolis”,“New York”,“Tokyo”,“London”);
	distance = new Array(
		new Array(0,648,6476,4000),
		new array(648,0,6760,3470),
		new array(6476,6760,0,5956),
		new array(4000,3470,5956,0)
	);


	function GetCity() {
		var theCity = “”;
		var cityMenu = “Please choose a city by typing in a number: \n\n”;
		cityMenu += “0) Indianapolis\n”;
		cityMenu += “1) New York\n”;
		cityMenu += “2) Tokyo\n”;
		cityMenu += “3) London\n”;

		theCity = prompt(cityMenu);
		return(theCity);
	}

	function main() {
		var output = “”;
		var from = GetCity();
		var to = GetCity();
		var result = distance;
		output = “The distance from “ + cityName;
		output += “ to “ + cityName;
		output += “ is “ + result + “ miles.”;
		alert (output);
	}

	main();

	
</script>

Replace all of those dodgy quote marks and change the three examples of ‘new array’ to ‘new Array’ then it should work.

Your code isn’t actually accessing the elements of your arrays.

I’ve simplified your code a bit: I’ve changed the array declarations to use simple literal arrays rather than using the Array() syntax. And I’ve added code to construct the menu prompt string from names in the cityName array appended to a passed in heading line. Also, I’ve embedded the script into a HTML page.

I couldn’t be hassled with trying to get it to display properly here, so I’ve put it on pastebin.

JTQ’s Distance Calculator