调用时函数未运行

Question

I have run into what I think is a rather simple problem, but cannot see the error. I have two functions that I am trying to call (one to display the date and another get focus on a text input box). When I run the web page nothing happens, so I am stumped.

I have created a fiddle here: http://jsfiddle.net/dk9D9/

And this is the specific javascript that I am working with.

var $ = function(id) { return document.getElementById(id); }

function todayTxt() {
   var today = new Date();
   return today.getMonth() + 1 + "-" + today.getDate() + "-" + today.getFullYear();
}

var initForm = function ()
{
    document.getElementById('qty1').focus()
}

window.onload = function () {
    $(initForm);
    $(todayTxt);
}

Any help is greatly appreciated.

Answer 1

You have defined initForm function as a variable. You should call it with:

initForm();

The same thing about todayTxt :

todayTxt();

$ function returns an element by given ID string as a parameter. The valid usage of it is:

$('elementId')

Valid code can looks like:

var $ = function(id) { return document.getElementById(id); }

function todayTxt() {
   var today = new Date();
   return today.getMonth() + 1 + "-" + today.getDate() + "-" + today.getFullYear();
}

var initForm = function() {
    $('qty1').focus();
}

window.onload = function() {
    initForm();
    todayTxt();
}

Answer 2

My guess is that you're not calling the function.

$(something); 

is retrieving something , but not calling it as a function.

Why are you using $(something) instead of calling initform(); as a regular function?

Answer 3

Following the call chain from the entry-point ( window.onload ), you are only actually calling 2 functions:

1. Your anonymous function for onload .
2. The $ function.

You have defined $ as document.getElementById(id) . When you call $ , you are passing references to the initForm and todayTxt function into $ as the id parameter.

In otherwords, when you call

$(initForm)

when entering $, we are calling

document.getElementById(initForm);

Since neither function has anything to do with $ , you probably are looking for:

window.onload = function () {
    initForm();
    todayTxt();
}

Answer 4

Seems like JSFiddle was calling onload on the JS input section so setting another onload function was preventing the code from running so I disabled it and made the necessary changes to make the page function.

http://jsfiddle.net/keWD5/

(You will need the window.onload call in your actual page.)