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Passing an array.push function in javascript

I have a problem passing an array.push function in javascript having a code like this:
const array = [];
addToArray("works", (e) => array.push(e));
addToArray("notWorks", array.push);
doConsoleLog("hello", console.log);
function addToArray(element, pushFn) {
pushFn(element);
}
function doConsoleLog(message, log) {
log(message);
}
Just curious how's that first call of addToArray works, but second causes TypeError: Cannot convert undefined or null to object. How is it possible? Type of array.push is a function. It is not possible to pass functions directly like in the case of console.log above, which works pretty well?

push is a method of array. When invoked, it uses this as a reference to the object it is being called on. If you pass it around like a normal function, you will lose that reference, the method will use the value of this defined at the moment of the call (inside addToArray, this is probably document.window), and will therefore fail.
In order to pass around a method, you need to bind it to the object you want it to operate on, in this case array. This is true for any object method in JavaScript. Function.prototype.bind() exists exactly for this purpose: it "binds" a function (in this case your method) to a given value of this, in order to work correctly.
const array = [];
addToArray("now it works", array.push.bind(array));
// or
addToArray("now it works", Array.prototype.push.bind(array));
function addToArray(element, pushFn) {
pushFn(element);
}

Once you pass a function like you did in the second case, it executes itself immediately, and array.push doesn't really mean something.
A callback function should be executed later on in the outer function.
Unlike the second example, in the first one you don't execute the function immediately, but only when you call it inside the outer function.

Your code have a lot of mistakes. What exactly should do this code? if you want to push new items in array use spread operator
const array = [...[], "works", "notWorks"]
const array = [];
addToArray("works", (e) => array.push(e));
addToArray("notWorks", array.push);
doConsoleLog("hello", console.log);
function addToArray(element, pushFn) {
pushFn(element); //function must return something
}
function doConsoleLog(message, log) {
log(message); //function must return something
}

Pull value from a function within a function

I have a map element that has multiple areas, and user can select one of those. Each area has an ID that represents a number (which I need to use in an equation later on).
How do I store the ID of selected area in a variable for later use?
My work so far:
function areaSelection(){
$("map").on('click', 'area', function (e){
e.preventDefault();
var areaSelect = parseInt(this.id);
console.log(areaSelect);
});
}
var mapSelection = areaSelection();
$("area").on('click', areaSelection);

Do your best to never use global variables.
Firstly, you're assigning a function call to a variable, which is returning undefined (all functions do this unless the return statement is used).
Secondly, the areaSelection function only creates the click event.
It doesn't actually calculate the areaSelect value.
Instead try something like this:
var mapSelection;
$("map").on('click', 'area', areaSelection);
function areaSelection(e) {
e.preventDefault();
mapSelection = parseInt(this.id);
}
This way, the mapSelection is getting set any time the map is clicked, but be aware that this is not likely to be efficient.

Javascript Window Function Pass "this" as Parameter

I am looping thru a JSON object and I want to set clicks on fields based on a function named in the JSON Object. The function called will by window[] will be parameterised instead of hardcoded.
for (var key in JSONOBJ) {
func = window["minRule"](this);
$('#'+ key).click(func);
}
The function being called is
function minRule(elem){
alert(elem.name);
}
and I want it applied to
<input type='text' name='FIELDINJSONOBJECT' id='FIELDINJSONOBJECT'/>
However when I refresh the page the function is being called for some reason and hasnt binded to the click. Also the alert(elem.name) is returning undefined. How do I pass this as the parameter to a function called with window[$FUNCTIONAME]
Regards,
Tom

I think what you are looking for is
$.each(JSONOBJ, function(key, value){
$('#'+ key).click(function(){
window["minRule"](value);
});
})
In your case you are invoking the function minRule in the loop with parameter this where it points to the current functions scope and the value returned by it (in this case undefined as the click handler), that is the reason it is not working

getting the name of a variable through an anonymous function

Is it possible to find the name of an anonymous function?
e.g. trying to find a way to alert either anonyFu or findMe in this code http://jsfiddle.net/L5F5N/1/
function namedFu(){
alert(arguments.callee);
alert(arguments.callee.name);
alert(arguments.callee.caller);
alert(arguments.caller);
alert(arguments.name);
}
var anonyFu = function() {
alert(arguments.callee);
alert(arguments.callee.name);
alert(arguments.callee.caller);
alert(arguments.caller);
alert(arguments.name);
}
var findMe= function(){
namedFu();
anonyFu();
}
findMe();
This is for some internal testing, so it doesn't need to be cross-browser. In fact, I'd be happy even if I had to install a plugin.

You can identify any property of a function from inside it, programmatically, even an unnamed anonymous function, by using arguments.callee. So you can identify the function with this simple trick:
Whenever you're making a function, assign it some property that you can use to identify it later.
For example, always make a property called id:
var fubar = function() {
this.id = "fubar";
//the stuff the function normally does, here
console.log(arguments.callee.id);
}
arguments.callee is the function, itself, so any property of that function can be accessed like id above, even one you assign yourself.
Callee is officially deprecated, but still works in almost all browsers, and there are certain circumstances in which there is still no substitute. You just can't use it in "strict mode".
You can alternatively, of course, name the anonymous function, like:
var fubar = function foobar() {
//the stuff the function normally does, here
console.log(arguments.callee.name);
}
But that's less elegant, obviously, since you can't (in this case) name it fubar in both spots; I had to make the actual name foobar.
If all of your functions have comments describing them, you can even grab that, like this:
var fubar = function() {
/*
fubar is effed up beyond all recognition
this returns some value or other that is described here
*/
//the stuff the function normally does, here
console.log(arguments.callee.toString().substr(0, 128);
}
Note that you can also use argument.callee.caller to access the function that called the current function. This lets you access the name (or properties, like id or the comment in the text) of the function from outside of it.
The reason you would do this is that you want to find out what called the function in question. This is a likely reason for you to be wanting to find this info programmatically, in the first place.
So if one of the fubar() examples above called this following function:
var kludge = function() {
console.log(arguments.callee.caller.id); // return "fubar" with the first version above
console.log(arguments.callee.caller.name); // return "foobar" in the second version above
console.log(arguments.callee.caller.toString().substr(0, 128);
/* that last one would return the first 128 characters in the third example,
which would happen to include the name in the comment.
Obviously, this is to be used only in a desperate case,
as it doesn't give you a concise value you can count on using)
*/
}

Doubt it's possible the way you've got it. For starters, if you added a line
var referenceFu = anonyFu;
which of those names would you expect to be able to log? They're both just references.
However – assuming you have the ability to change the code – this is valid javascript:
var anonyFu = function notActuallyAnonymous() {
console.log(arguments.callee.name);
}
which would log "notActuallyAnonymous". So you could just add names to all the anonymous functions you're interested in checking, without breaking your code.
Not sure that's helpful, but it's all I got.

I will add that if you know in which object that function is then you can add code - to that object or generally to objects prototype - that will get a key name basing on value.
Object.prototype.getKeyByValue = function( value ) {
for( var prop in this ) {
if( this.hasOwnProperty( prop ) ) {
if( this[ prop ] === value )
return prop;
}
}
}
And then you can use
THAT.getKeyByValue(arguments.callee.caller);
Used this approach once for debugging with performance testing involved in project where most of functions are in one object.
Didn't want to name all functions nor double names in code by any other mean, needed to calculate time of each function running - so did this plus pushing times on stack on function start and popping on end.
Why? To add very little code to each function and same for each of them to make measurements and calls list on console. It's temporary ofc.
THAT._TT = [];
THAT._TS = function () {
THAT._TT.push(performance.now());
}
THAT._TE = function () {
var tt = performance.now() - THAT._TT.pop();
var txt = THAT.getKeyByValue(arguments.callee.caller);
console.log('['+tt+'] -> '+txt);
};
THAT.some_function = function (x,y,z) {
THAT._TS();
// ... normal function job
THAT._TE();
}
THAT.some_other_function = function (a,b,c) {
THAT._TS();
// ... normal function job
THAT._TE();
}
Not very useful but maybe it will help someone with similar problem in similar circumstances.

arguments.callee it's deprecated, as MDN states:
You should avoid using arguments.callee() and just give every function
(expression) a name.
In other words:
[1,2,3].forEach(function foo() {
// you can call `foo` here for recursion
})
If what you want is to have a name for an anonymous function assigned to a variable, let's say you're debugging your code and you want to track the name of this function, then you can just name it twice, this is a common pattern:
var foo = function foo() { ... }
Except the evaling case specified in the MDN docs, I can't think of any other case where you'd want to use arguments.callee.

No. By definition, an anonymous function has no name. Yet, if you wanted to ask for function expressions: Yes, you can name them.
And no, it is not possible to get the name of a variable (which references the function) during runtime.

Remembering the last value passed to a JavaScript function called on click

Below is my code fragment:
<div onclick = "myClick('value 1')">
button 1
</div>
<div onclick = "myClick('value 2')">
button 2
</div>
Basically when I for each click on a different div, a different value will be passed to the JavaScript function.
My Question is how can I keep track of the value passed in the previous click?
For example, I click "button 1", and "value 1" will be passed to the function. Later, I click on "button 2", I want to be able to know whether I have clicked "button 1" before and get "value 1".

Just add it to a variable in your script:
var lastClicked;
var myClick = function(value) {
lastClicked = value;
};

You can define somekind of variable, like var lastUsed;
add additional line to your function:
var lastUsed = null;
function myClick(value){
prevClicked = lastUsed; //get the last saved value
...
lastUsed = value; //update the saved value to the new value
...
}
And here you go

You need a variable. Variables are like little boxes in which you can store values. In this case, we can store the value that was last passed to the function myClick.
In Javascript, you can define a variable like this:
var lastClickedValue;
You can "put" a value into that variable. Let's say you want to put your name in there. You would do this:
lastClickedValue = 'sams5817';
Now here's the tricky bit. Variables have "scope". You might want to think about it as their "life-time". When a variable reaches the end of its scope, you cannot read or write to it anymore. It's as if it's never been. Functions define a scope. So any variable you define in a function will disappear at the end of the function. For example:
function myClick(value)
{
var lastClickedValue;
alert('lastClickedValue is = ' + value);
lastClickedValue = value;
}
That looks almost right, doesn't it? We declared a variable, display its last value, and update it with the new value.
However, since the lastClickedValue was declared in the function myClick, once we've reached the end of that function, it's gone. So the next time we call myClick, lastClickedValue will be create all over again. It will be empty. We call that an "uninitialized" variable.
So what's the problem? We're trying to remember a value even after the end of myClick. But we declared lastClickedValue inside myClick, so it stops existing at the end of myClick.
The solution is to make sure that lastClickedValue continues to exist after myClick is done.
So we must delcare lastClickedValue in a different scope. Luckily, there's a larger scope called the "global scope". It exists from the moment your page loads, and until the user moves on to another webpage. So let's do it this way:
var lastClickedValue;
function myClick(value)
{
alert('lastClickedValue is = ' + value);
lastClickedValue = value;
}
It's a very small difference. We moved the declaration of the variable lastClickedValue to be outside the function myClick. Since it's outside, it will keep existing after myClick is done. Which means that each time we call myClick, then lastClickedValue will still be there.
This will let you know what the last value passed to myClick was.
Finally, I'd like to advise you to look for some kind of Javascript tutorials. I wish I knew of some good ones to recommend, but I'm certain you can find a few on the Internet. If you try to write programs before understanding what you're doing, you'll find yourself producing work that is less than what you're capable of. Good luck!

I suppose you need something like this
var clickedButtons = [];
function myClick(value){
...
clickedButtons.push(value);
...
}

I am surprised that no one else mentioned this, but since functions are first class objects in JavaScript, you can also assign attributes and methods to functions. So in order to remember a value between function calls you can do something like I have with this function here:
function toggleHelpDialog() {
if (typeof toggleHelpDialog.status === 'undefined')
toggleHelpDialog.status = true;
else
toggleHelpDialog.status = !toggleHelpDialog.status;
var layer = this.getLayer();
if (toggleHelpDialog.status) layer.add(helpDialog);
else helpDialog.remove();
layer.draw();
}
Here I have added an attribute named 'status' to the toggleHelpDialog function. This value is associated with the function itself and has the same scope as the toggleHelpDialog function. Values stored in the status attribute will persist over multiple calls to the function. Careful though, as it can be accessed by other code and inadvertently changed.

we can leverage javascript static variables
One interesting aspect of the nature of functions as objects is that you can create static
variables. A static variable is a variable in a function‘s local scope whose value persists across
function invocations. Creating a static variable in JavaScript is achieved by adding an instance
property to the function in question. For example, consider the code here that defines a function
doSum that adds two numbers and keeps a running sum:
function doSum(x,y){
if (typeof doSum.static==='undefined'){
doSum.static = x+y;
}else{
doSum.static += x+y;
}
if (doSum.static >= 100){doSum.static = 0;doSum.static += x+y;}
return doSum.static;
}
alert(doSum(5,15))
alert(doSum(10,10))
alert(doSum(10,30))
alert(doSum(20,30))