I have this function that checks a UK postcode. The problem is that it never returns true or false - only undefined .
function PostcodeAnywhere_Interactive_FindByPostcode_v1_00(Key, Postcode, UserName) {
var retval;
$.getJSON("https://services.postcodeanywhere.co.uk/PostcodeAnywhere/Interactive/FindByPostcode/v1.00/json3.ws?",
{
Key: Key,
Postcode: Postcode,
UserName: UserName
},
function (response) {
// Test for an error
if (response.Items.length == 1 && typeof(response.Items[0].Error) != "undefined") {
// Show the error message
retval = false;
} else {
// Check if there were any items found
if (response.Items.length == 0){
retval = false;
} else {
retval = true;
}
}
});
return retval;
}
To me it looks like it should always return true or false , so I can't understand where I'm going wrong. Can someone please help? Is it that the getJSON function needs time to execute?
It returns undefined because $.getJSON runs asynchronously and so retval is returned before the success function of $.getJSON is executed. If you need to use retval you must call the function that uses it in the callback
ReplyDelete$.getJSON("https://services.postcodeanywhere.co.uk/PostcodeAnywhere/Interactive/FindByPostcode/v1.00/json3.ws?",
{
Key: Key,
Postcode: Postcode,
UserName: UserName
},
function (response) {
// Test for an error
if (response.Items.length == 1 && typeof(response.Items[0].Error) != "undefined") {
// Show the error message
retval = false;
} else {
// Check if there were any items found
if (response.Items.length == 0){
retval = false;
} else {
retval = true;
}
//use retval
do_something_with_retval(retval);
}
});