Undefined function when using IFFE (Immediately-invoked function expression) - javascript

I've got a function which I've assigned to a variable and when I instantly invoice it with IFFE, I get an undefined error.
<script>
"use strict";
$(document).ready(function () {
var enableBulkAction = function () {
if ($("#frmProductManagement input:checkbox:checked").length > 0) {
// any one is checked
$('#ddlBulkAction').prop("enabled", "enabled");
} else {
// none is checked
$('#ddlBulkAction').prop("disabled", "disabled");
}
}();
$('#chkTableAll').click(function () {
var checkedStatus = this.checked;
$('#tblProductsManagements tbody tr').find('td:first :checkbox').each(function () {
$(this).prop('checked', checkedStatus);
enableBulkAction();
});
});
});
</script>
enableBulkAction(); is not a function even though it should be in scope. Anyone know what I've forgotten to do?

What you will want to do to change this, if you want the enableBulkAction to be available for reference AND you want to invoke it right away is to make this change:
var enableBulkAction = function () {
if ($("#frmProductManagement input:checkbox:checked").length > 0) {
// any one is checked
$('#ddlBulkAction').prop("enabled", "enabled");
} else {
// none is checked
$('#ddlBulkAction').prop("disabled", "disabled");
}
};
enableBulkAction();
The rest of the script can remain as is.

Related

how to destroy a function in another function javascript?

Function:
function abc()
{
$('#table_id tr td').removeClass('highlight');
$(this).addClass('highlight');
tableText($table_label,$table_id);
}
abc();
function refresh()
{
abc().hide; // Need help at this.
}
<button class="refresh" onclick="refresh()">Refresh</button>
I'm trying to remove function/stop running abc() function, when refresh button was clicked.
Try this code, if abc is in the global scope:
window.abc = function() {
return false;
}
or you could do: window.abc = undefined when it's in the global scope.
when it's a method: delete obj.abc
You can pass param in your function and check condition like below.
function abc(arg) {
if (arg) {
$('#table_id tr td').removeClass('highlight');
$(this).addClass('highlight');
tableText($table_label, $table_id);
} else {
//Do what ever you want if needed
}
}
abc(true);
function refresh() {
abc(false)
}
Put all the code you only want to run once at the start inside window.onload
window.onload = function() {
$('#table_id tr td').removeClass('highlight');
$(this).addClass('highlight');
tableText($table_label,$table_id);
}
Wrap the function inside an object to delete it. You can use the window object or create a new one. Example:
const functions = new Object;
functions.abc = () => { /* do something */ };
functions.abc();
const refresh = () => {
if ('abc' in functions){ functions.abc(); delete functions.abc; }
else { /* will do nothing */ }
};
Solved :-)

Starting and ending functions in javascript

I am playing around with a short little code to see if I can get a function going while the user has their mouse down and then end it when they bring their mouse up. For this example I am trying to increment a number that I am displaying on the screen as the user moves their mouse while holding the button down. I want it to freeze and stop once they release the button, however the counter just resets and the count continues from 0 even though the button is not being pressed...
function dragInit(state, e) {
var i = 0;
$(document).on("mousemove", function() {
if (state) {
i+=1;
$('#debug').text(i); //Show the value in a div
}
});
}
$(document).ready(function() {
$(document).on(
{mousedown: function(e) {
var state = true;
dragInit(e, state);
},
mouseup: function(e) {
var state = false;
dragInit(e, state);
}
});
});
As an aside, is there a way I can display whether a variable is true or false onscreen? When I try it just says [object Object].
There are a lot of mistakes in your code. I suggest you to read more basic concepts before starting to use jQuery.
The order of the parameters passed to dragInit() is wrong on both mouseup and mousedown event bindings.
The reason your counter is restarting is because your variable i is local, so it exists only during the function context it is declared in.
You are making the same mistake with the state variable, but in this case it is completely unnecessary to declare it.
Consider making your counter a global (even though it is not a good practice).
I can't provide you code because I am answering from my phone. A solution would be create a mousemove event that checkes whether the mouse button is pressed before incrementing your counter.
Hope I helped
You could do something like this:
function dragInit() {
$(document).on("mousemove", function () {
if (eventState.state) {
eventState.count += 1;
$('#debug').text(eventState.count); //Show the value in a div
}
});
}
// Create an object to track event variables
var eventState = {
count:0, //replaces your previous 'i' variable
state: false //keeps track of mouseup or mousedown
};
$(document).ready(function () {
$(document).on({
mousedown: function (e) {
eventState.state = true;
dragInit(); //don't need to pass anything anymore
},
mouseup: function (e) {
eventState.state = false;
dragInit(); //don't need to pass anything anymore
}
});
});
jsFiddle
Or keep everything together as one object
var dragInit = function () {
var count = 0;
var state = false;
var action = function () {
$(document).on("mousemove", function () {
if (state) {
count += 1;
$('#debug').text(count); //Show the value in a div
}
})
};
$(document).on({
mousedown: function (e) {
state = true;
action(); //don't need to pass anything anymore
},
mouseup: function (e) {
state = false;
action(); //don't need to pass anything anymore
}
});
}
$(document).ready(function () {
var obj = new dragInit();
});
jsFiddle 2
Example in response to comment
jsFiddle: This shows why the following code snippets differ in execution.
// Works
$(document).on("mousemove", function () {
if (state) {
}
})
// Doesn't
if (state) {
$(document).on("mousemove", function () {
});
}
Less code, You just need this.
Use jquery on and Off to turn on and off mousemove event.
Counter Reset http://jsfiddle.net/kRtEk/
$(document).ready(function () {
var i = 0;
$(document).on({
mousedown: function (e) {
$(document).on("mousemove", function () {
$('#debug').text(i++); //Show the value in a div
});
},
mouseup: function (e) {
i = 0;
$('#debug').text(i);
$(document).off("mousemove");
}
});
});
W/O Reset http://jsfiddle.net/gumwj/
$(document).ready(function () {
var i = 0;
$(document).on({
mousedown: function (e) {
$(document).on("mousemove", function () {
$('#debug').text(i++); //Show the value in a div
});
},
mouseup: function (e) {
$(document).off("mousemove");
}
});
});
WithNoCounter http://jsfiddle.net/F3ESx/
$(document).ready(function () {
$(document).on({
mousedown: function (e) {
$(document).on("mousemove", function () {
$('#debug').data('idx',parseInt($('#debug').data('idx')|0)+1).text($('#debug').data('idx')); //Show the value in a div
});
},
mouseup: function (e) {
$(document).off("mousemove");
}
});
});
Assuming you are married to Jquery (nothing wrong with that) - check out and consider entirely re-thinking your approach leveraging the ".one()" (http://api.jquery.com/one/) method.
edit: and if that taste doesn't sit well - familiarize yourself with the "deferred" object (http://api.jquery.com/category/deferred-object/)
lots of ways to approach this via jquery - what you decide in the end depends on what you really intend to do with this.

Self invoking function that can be called as well

The following code works, but I'd like to use the self-invoking function syntax when declaring it instead of calling it explicitly on the last line:
var ShowMe = function() {
if ($('input:checkbox:checked').length) {
$('#Save').fadeIn('slow');
} else {
$('#Save').hide();
}
};
$('input:checkbox').on('click',ShowMe);
ShowMe();
You can't declare the var inside of an expression, but you can put its definition in one:
var ShowMe; (ShowMe = function() {
if ($('input:checkbox:checked').length) {
$('#Save').fadeIn('slow');
} else {
$('#Save').hide();
}
})();
$('input:checkbox').on('click',ShowMe);
Try this instead:
var ShowMe = function() {
if ($(this).length) { // `this` is the input that was clicked
$('#Save').fadeIn('slow');
} else {
$('#Save').hide();
}
};
$('input:checkbox').on('click', ShowMe).trigger('click');
Update based on comments below:
$('#Save').hide();
$('input:checkbox').on('click', function() {
if(this.checked) { //check if this is checked
$('#Save').show('slow');
}
else if(!($('input[type="checkbox"]:checked').length)) {
//check to see if anything else was checked
$('#Save').hide();
}
});

Is it possible to bind to the Click event and not use an anonymous function -- I just want to call a named function

I have the following code. The first attempt at binding to click event does not work. The second way does. The first shows the alert "CheckBox1" during Page_Load. The second one shows the alert "CheckBox4" during the proper time -- during clicks.
$(document).ready(function () {
$(document.getElementById(checkBox1ID)).click( SetCheckBox1State(this.checked) );
$(document.getElementById(checkBox4ID)).click(function () { SetCheckBox4State(this.checked) });
});
function SetCheckBox1State(checked) {
alert("CheckBox2");
var radNumericTextBox1 = $find(radNumericTextBox1ID);
var wrapperElement = $get(radNumericTextBox1._wrapperElementID);
var label = $(wrapperElemenet.getElementsByTagName("label")[0]);
if (checked) {
radNumericTextBox1.enable();
label.addClass("LabelEnabled");
label.removeClass("LabelDisabled");
}
else {
radNumericTextBox1.disable();
label.addClass("LabelDisabled");
label.removeClass("LabelEnabled");
}
}
function SetCheckBox4State(checked) {
alert("CheckBox4");
var radNumericTextBox2 = $find(radNumericTextBox2ID);
var wrapperElement = $get(radNumericTextBox2._wrapperElementID);
var label = $(wrapperElemenet.getElementsByTagName("label")[0]);
if (checked) {
radNumericTextBox2.enable();
label.addClass("LabelEnabled");
label.removeClass("LabelDisabled");
}
else {
radNumericTextBox2.disable();
label.addClass("LabelDisabled");
label.removeClass("LabelEnabled");
}
}
Am I doing something improper? I'd rather not use an anonymous function...but maybe this just how things work?
This code:
.click( SetCheckBox1State(this.checked) );
Assigns the .click() function to be the output of this function: SetCheckBox1State(this.checked).
You will have to get rid of the argument (make it internal) and just pass the function name:
.click( SetCheckBox1State );

javascript - recursive function & setTimeout

I am trying to write a javascript function that when called performs function DoSomething() once,
but can be triggered to perform the function repeatedly until triggered to stop.
I am using setTimeout() function. I am not sure if this is best method from performance and memory point of view.
Also I would like to avoid global variable if possible
<!DOCTYPE html>
<html>
<script src="jquery.js"></script>
<script>
var globalCheckInventory = false;
$(document).ready(function(){
// start checking inventory
globalCheckInventory = true;
myTimerFunction();
});
// check inventory at regular intervals, until condition is met in DoSomething
function myTimerFunction(){
DoSomething();
if (globalCheckInventory == true)
{
setTimeout(myTimerFunction, 5000);
}
}
// when condition is met stop checking inventory
function DoSomething() {
alert("got here 1 ");
var condition = 1;
var state = 2 ;
if (condition == state)
{
globalCheckInventory = false;
}
}
</script>
This is probably the easier way to do what you're describing:
$(function () {
var myChecker = setInterval(function () {
if (breakCondition) {
clearInterval(myChecker);
} else {
doSomething();
}
}, 500);
});
Another way to do it would be the store the timer ID and use setInterval and clearInterval
var timer = setInterval(DoSomething);
function DoSomething() {
if (condition)
clearInterval(timer);
}
I see nothing wrong with your implementation other than the pollution of the global namespace. You can use a closure (self-executing function) to limit the scope of your variables like this:
(function(){
var checkInventory = false, inventoryTimer;
function myTimerFunction() { /* ... */ }
function doSomething() { /* ... */ }
$(document).ready(function(){
checkInventory = true;
/* save handle to timer so you can cancel or reset the timer if necessary */
inventoryTimer = setTimeout(myTimerFunction, 5000);
});
})();
Encapsulate it:
function caller(delegate, persist){
delegate();
if(persist){
var timer = setInterval(delegate, 300);
return {
kill: function(){
clearInterval(timer);
}
}
}
}
var foo = function(){
console.log('foo');
}
var _caller = caller(foo, true);
//to stop: _caller.kill()

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