i thought i know what I was doing - calling a function from a string

[windandwaves]

Hi Folk

Consider the following function:

function UpdateHtml(url, parameters, onready) {
http_request = false;
if (window.XMLHttpRequest) { // Mozilla, Safari,...
http_request = new XMLHttpRequest();
if (http_request.overrideMimeType) {
// set type accordingly to anticipated content type
http_request.overrideMimeType('text/xml');
//http_request.overrideMimeType('text/html');
}
}
else if (window.ActiveXObject) { // IE
try {
http_request = new ActiveXObject("Msxml2.XMLHTTP");
}
catch (e) {
try {
http_request = new ActiveXObject("Microsoft.XMLHTTP");
}
catch (e) {
alert('could not load data');
}
}
}
if (!http_request) {
alert('Cannot create XMLHTTP instance');
return false;
}
//var onreadyfunction = new function() { eval(onready);}
http_request.onreadystatechange = updatemap;
var geturl = url + '?' + parameters;
document.getElementById(idname + 'title').innerHTML = "loading new map
.... " + geturl;
http_request.open('GET', geturl, true);
http_request.async = false;
http_request.send(null);
}

It opens xml and assigns a function that should run when it is loaded.


In the form above, it works, however, I want it to work with the
variable that I pass. When I rewrite the JS below from:
//var onreadyfunction = new function() { eval(onready);}
http_request.onreadystatechange = updatemap;
to
var onreadyfunction = new function() { eval(onready);}
http_request.onreadystatechange = onreadyfunction;
it does not work

what am I doing wrong?

Thanks heaps in advance

Nicolaas

 

[pcx99]

In the form above, it works, however, I want it to work with the
variable that I pass. When I rewrite the JS below from:
//var onreadyfunction = new function() { eval(onready);}
http_request.onreadystatechange = updatemap;
to
var onreadyfunction = new function() { eval(onready);}
http_request.onreadystatechange = onreadyfunction;
it does not work

what am I doing wrong?

http_request.onreadystatechange = function() { eval(onready); }


Ditch the new. Ditch trying to use a variable to hold the function. I
would also note that doing a JSON eval in this context is pretty
dangerous since you're not doing a check of the readystate nor the
status of the data. Of course there's no surprise there. I'm not a
big fan of JSON and eval but to each his own.

G'luck!

 

[windandwaves]

http_request.onreadystatechange = function() { eval(onready); }


Ditch the new. Ditch trying to use a variable to hold the function. I
would also note that doing a JSON eval in this context is pretty
dangerous since you're not doing a check of the readystate nor the
status of the data. Of course there's no surprise there. I'm not a
big fan of JSON and eval but to each his own.

Thanks a million. It is dangerous, but it works - for now

Thanks