Question

if(document.frmMain.POL_NO.value == "")
{
    alert("Select Policy Number");
    document.frmMain.ENDT_NO.value="";
    document.frmMain.POL_NO.focus();
    return false;           
}

Can anyone explain the above code to me? I am new to Javascript.

Answer 1

It appears to be a bit of validation code to make sure a user has entered a value for an item referred to as “Policy Number”. It is the sort of code that gets called when submitting a form to check that the values the user has entered are valid.

In detail:

if(document.frmMain.POL_NO.value == "")

Only run this code if the item called in POL_NO the form called frmMain doesn’t have a value yet.

alert("Select Policy Number");

Display a message to tell the user that they need to enter a value.

document.frmMain.ENDT_NO.value="";

Set the ENDT_NO item of frmMain to a blank value.

document.frmMain.POL_NO.focus();

Set the focus to the POL_NO item (the same as the user tabbing to it or clicking on it).

return false;

Return false to the code that called the function that this code is in. If this code is used in the event handler for the submit button on a form then returning false will stop the form from being submitted to the server until the POL_NO item has a value.