Develop Reference

Lazy loading. Why do I see the result of the JavaScript only when it is fully run through? [duplicate]

Why does this function get fired without having clicked on the specified button?
I had a look at a few similar problems but none deal with this code structure (might be obvious reason for this im missing...).
document.getElementById("main_btn").addEventListener("click", hideId("main");
function hideId(data) {
document.getElementById(data).style.display = "none";
console.log("hidden element #"+data);
}

You are directly calling it.
document.getElementById("main_btn").addEventListener("click", hideId("main");
You should do that in a callback.
document.getElementById("main_btn").addEventListener("click", function (){
hideId("main");
});

This code executes your function hideId("main") you should pass just the callback's name:
document.getElementById("main_btn").addEventListener("click", hideId);
function hideId(event) {
var id = event.target.srcElement.id; // get the id of the clicked element
document.getElementById(data).style.display = "none";
console.log("hidden element #"+data);
}

document.getElementById("main_btn").addEventListener("click", hideId.bind(null, "main");

JS prevent a function from running as onclick event

I would like to disable a certain function from running as an onclick event.
Here, I would like to disable myfunc1, not myfunc2. Actually I want to disable myfunc1 from the whole page, but anyway this is the only thing that I need.
I have no control over the page and I am using userscript or other script injection tools to achieve this.
What I've tried:
Redefining the function after the page has loaded: I've tried adding an event listener to an event DOMContentLoaded with function(){ myfunc1 = function(){}; }
This seems to be working, but in a fast computer with fast internet connection, sometimes it runs before the myfunc1 is defined (in an external js file that is synchronously loaded). Is there any way that I can guarantee that the function will be executed after myfunc1 is defined?
Is there any way that I can 'hijack' the onclick event to remove myfunc1 by its name?

You should use event listeners, and then you would be able to remove one with removeEventListener. If you can't alter the HTML source you will need something dirty like
function myfunc1() {
console.log('myfunc1');
}
function myfunc2() {
console.log('myfunc2');
}
var a = document.querySelector('a[onclick="myfunc1();myfunc2();"]');
a.setAttribute('onclick', 'myfunc2();');
Click me
Or maybe you prefer hijacking the function instead of the event handler:
function myfunc1() {
console.log('myfunc1');
}
function myfunc2() {
console.log('myfunc2');
}
var a = document.querySelector('a[onclick="myfunc1();myfunc2();"]');
var myfunc1_;
a.parentNode.addEventListener('click', function(e) { // Hijack
if(a.contains(e.target)) {
myfunc1_ = window.myfunc1;
window.myfunc1 = function(){};
}
}, true);
a.addEventListener('click', function(e) { // Restore
window.myfunc1 = myfunc1_;
myfunc1_ = undefined;
});
Click me

Another way this could be done is using Jquery and setting the onlick propery on the anchor tag to null. Then you could attach a click function with just myfunc2() attached.
$(document).ready(function () {
$("a").prop("onclick", null);
$("a").click(function(){
myfunc2();
});
});
function myfunc1() {
console.log('1');
}
function myfunc2() {
console.log('2');
}
<a class="test" href="#" onclick="myfunc1();myfunc2();">Example</a>
You can see the codepen here - http://codepen.io/anon/pen/BLBYpO

Perhaps you are into jQuery.
$(document).ready(function(){
var $btn = $('button[onclick*="funcOne()"]');
$btn.each(function(){
var newBtnClickAttr;
var $this = $(this);
var btnClickAttr = $this.attr("onclick");
newBtnClickAttr = btnClickAttr.replace(/funcOne\(\)\;/g, "");
$this.attr("onclick", newBtnClickAttr);
});
});
Where in the variable $btn gets all the button element with an onclick attribute that contains funcOne().
In your case, this would be the function you would like to remove on the attribute e.g., myfunc1();.
Now that you have selected all of the elements with that onclick function.
Loop them and get there current attribute value and remove the function name by replacing it with an empty string.
Now that you have the value which does not contain the function name that you have replace, you can now update the onclick attribute value with the value of newBtnClickAttr.
Check this Sample Fiddle

Function out of scope?

I have a function defined as follows:
window.onload = function() {
var ids = document.getElementById("idname");
function myFunction(){
/...*use ids var in here*./
}
}
I am trying to call myFunction from button onclick in html:
<button onclick="myFunction();"></button>
But it says myFunction is not defined. I understand because this is inside window.onload. How can I fix this? I need window.onload because I need to use document.getElementById("testID") to get content.

I need window.onload because I need to use document.getElementById("testID") to get content
No, you don't need window.onload. You simply have to put the code somewhere after the element with ID testID in the document.
Example:
<div id="testID"></div>
<script>
var ids = document.getElementById("testID");
function myFunction(){
/...*use ids var in here*./
}
</script>
However, if you want to keep using window.onload, then I suggest to not use inline event handlers, but bind the handler with JS:
window.onload = function() {
var ids = document.getElementById("testID");
ids.onclick = function(event){
/...*use ids var in here*./
}
};
(that might be a good thing to do anyway).
Lastly, you can get the a reference to the element inside the event handler using this or event.target:
<div id="testID"></div>
<script>
document.getElementById("testID").onclick = function(event) {
// access element via `this` or `event.target`
};
</script>
Learn more about event handling.

You defined it within a function so it's locked to that scope. Maybe you want to define it outside of that:
function myFunction() {
var ids = document.getElementById("idname");
// ...
}
window.onload = function() {
// ...
}
As a note, this is extremely old-school JavaScript. You could clean this up considerably using something like jQuery which would look something like this:
$(function() {
// Any initialization after page load.
});
function myFunction() {
var ids = $('#idname');
// ...
}

Have the element who call my js function

I know my question have answer in the past but I don't have the vocabulary to find this.
I call a JavaScript function like this:
Voir +
This function change the state of the element .stats-table but I want to know which button have been clicked to call this function?
Better : can I have a jQuery object of this button?

Try to pass the this reference to know which button was clicked,
HTML:
Voir +
JS:
function showTable(selec,elem){
var currentElem = $(elem); //Clicked element
}

If you don't want to change the signature of the function and the way you invoke it (as others have suggested), you can use the global window.event to identify the clicked element:
function showTable(selector)
{
var clickedElement = window.event.target;
//...
}
See MDN.

When you use jQuery, you might consider refactor your code like this:
$(document).ready(function(){
$('.show-table-link').on('click', function(){
var $usedButton = $(this)
showTable('.stats-table')
}
})
Voir +
It's good practice to attach the on click handler instead of writing it inline. Further reading document.ready and jQuery event basics.

You can pass any value or id and your can identify the function
<script type="text/javascript">
function showTable(clss_name,fun_id)
{
if(fun_id=='A1')
{
alert("First function Executed");
}
if(fun_id=='A2')
{
alert("Second Function is executed");
}
}
</script>
......
......
......
Voir +
Voir2 +

If your function is like this:
function showTable(selec) {
// some code
}
You can get the clicked element like this, using this:
function showTable(selec) {
// some code
var clickedElem = this;
}

Javascript pass parameter to function

i try to pass paramater to function. When i click the div it will alert the paramater that i pass
i have 2 file
index.html
script.js
here's what i try
Example 1
index.html
<div id="thediv" >
script.js
window.onload = initialize;
//bind event listener
function initialize(){
document.getElementById("thediv").onclick = myFunction(" something ");
}
//end of bind
//function
function myFunction(parameter) { alert( parameter ) };
//end of all function
the trouble is the function its executed without click
Example 2
index.html
<div id="thediv" onclick="myfunction('something')" >
script.js
function myFunction(parameter) { alert( parameter ) };
yap its done with this but the trouble if i have many element in index.html it will painful to read which element have which listener
i want to separate my code into 3 section (similiar with example1)
the view(html element)
the element have which listener
the function
what should i do? or can i do this?
(i don't want to use another library)

Placing () (with any number of arguments in it) will call a function. The return value (undefined in this case) will then be assigned as the event handler.
If you want to assign a function, then you need to pass the function itself.
...onclick = myFunction;
If you want to give it arguments when it is called, then the easiest way is to create a new function and assign that.
...onclick = function () {
myFunction("arguments");
};

Your first solution logic is absolutely ok .. just need to assign a delegate ... what you are doing is calling the function .. So do something like this ...
//bind event listener
function initialize(){
document.getElementById("thediv").onclick = function () { myFunction(" something "); };
}
//end of bind

Instead of assign you invoke a function with myFunction();
Use it like this
//bind event listener
function initialize(){
document.getElementById("thediv").onclick = function(){
myFunction(" something ");
}
}