What happens if you do this?
function Person() {}
Person.prototype = 7;
var ted = new Person();
Also what happens if you set Person.prototype to an array or function?
Array.prototype.each = function (fn) {
this.map(fn)
}
This is my each function that works great in every other browser but IE. UGH! What am I doing wrong? the error points to the this in the function. Is it that IE doesn't like map? Has anyone seen this before? I thought my code was correct. Works perfect in FF, chrome and opera. the canvas text doesn't work in opera, but it does render the features so the each function is working.
I'll post the code if needed, but it's huge. here's the script running.[URL]..
I found this code on Internet:
<script type="text/javascript">
Array.prototype.push = function() {
var n = this.length >>> 0;
for (var i = 0; i < arguments.length; i++) {
this[n] = arguments[i];
n = n + 1 >>> 0;
}
this.length = n;
return n;
};
</script>
Question 1: How to call this function?
Question 2: When I delete >>> 0, what I lose? ( >>>0 ı sildiğim zaman, ne kaybederim?)
In the below code, the alert message returns in one instance: 'someAnimal is [Mammal "Mr. Biggles"]' I don't understand how this is possible. We pass as an argument 'Mr. Biggles' to the Mammal constructor. Then assign it to the object name property. But then it ends there. There is a function called toString which will return the alert. But the toString function is not being called like this: alert('someAnimal is '+someAnimal.toString()); If it was like how it is above, it would make sense to me but now it makes no sense to me because I don't see where that toString() is being called - I only see that it is prototyped to the Mammal object.
Code:
function Mammal(name){
this.name=name;
this.offspring=[];
}
Mammal.prototype.haveABaby=function(){
var newBaby=new Mammal("Baby "+this.name);
this.offspring.push(newBaby);
[Code]....
I've ammended my code now so that I'm using objects, constructors and prototypes.
If I use the standard constructor.prototype.functionname = (){......} type of setup it works okay.
However I'm now experimenting with overwriting the prototype with a literal. As in the code below. i.e. constructor.prototype = {functionname : function() .......
Doing it this way my first new object instance fails. The subsequent new objects are fine.
I ran a check on the properties of the 1st object with '!hasOwnProperty and name in' and the result is that the prototype (or pointer to a prototype) is missing.
So the first new object of FontTrans (oH) has
Code:
1 property is Heading
.
.
9 property is Delay
[Code].....
I was hoping I could do something like this in javascript:
var a = {x:1, y:2};
var b = {x:2, z:3};
b.prototype = a;
And then:
b.x => 2
b.y => 2
b.z => 3
The purpose is to set up "b" as an override of "a".
I know it doesn't work that way because "prototype" is not a magic property on any object but constructors only. Is there a way to implement the above without involving a constructor?
I had read from books that the constructor property of object is inherited from its prototype. And the prototype can be changed dynamically. New property can be added to or deleted from object even it was created before the prototype change.
But I got confused on below codes.
But the actual result (both IE and firefox) is
According to ECMAScript, the root of the prototype chain is Object.Prototype. Each object has an internal property [[Prototype]] that could be another object or NULL.... However, it also says that every function has the Function prototype object: Function.Prototype, it confused me, because a function is an object, for a function object, what is its function prototype and object prototype..For example:
var x = function (n) {return n+1;};
what is the relationships of x, Object.Prototype and Function.Prototype
I am trying to get to the bottom of javascript object, prototypes etc. I have a fairly good grasp of it, but I get confused the closer I get to the base object.prototype. FIrst of all, I was under the impression that all objects descend directly from Object. But some objects (like Array) seem to inherit properties and methods from the function.prototype. So does this mean that the chain is like this:
object -- function -- array Second, I noticed (on the mozilla javascript reference site that object.prototype inherits properties and methods from function.prototype and vice versa!? How can this be? I must be missing something important about understanding the chain?
I am building a customised javascript prototype to sort an associative array on the array key (in ascending order). Basically, I am separating the array keys into a separate array and then using .sort() to sort the keys and then reassembling the original associative array elements according to the sorted keys array.
The sorting works ok except that when I run the test code below, the outputed sorted associative array has an extra element at the end of the array whose key is the name of the prototype function and the value for that element is the function code itself. Obviously I am misunderstanding something about associative arrays or how javascript prototypes work.
[Code]...
Is there a way to access the value assigned to onmousedown for an
object? I've been searching online but can only seem to find how it is
assigned via html. What I need to do is access the value (the script
string) in javascript.
For example, I'd like to try to do something like this:
function virtualClick(objectName) {
eval(document.getElementById(objectName).onmousedo wn);
}
I am of course not explaining the full problem in detail, but would
appreciate any input on how to access the onmousedown value (or to know
if it even exists as a property).
The code works as expected in Chrome, but not in IE and FF. In IE the error is "Object doesn't support this action" and in FF "setting a property that has only a getter". In Chrome there is no error in the console. There are three javascript <script>...</script>s that exist to display a <td> row in a table with a particular graphic depending on the screen width. The odd thing is that in both IE and FF (and of course Chrome), the first two scripts display perfectly well. Why does the third <script> produce an error? It has exactly the same form as the two before it.
I can only guess it has something to do with where it occurs :confused: Googling the FF error, it has something to do with trying to set a read-only property, but then why do the first two <scripts> work? They are no different (at least I can't see a difference.)
[Code]...
Trying to add a new property to a non-jQuery object from inside each loop doesn't appear to work:
var arguments=new Object();
arguments['ticket']=ticket;
arguments['email']=email;
arguments['module']=module;
arguments['epoch']=new Date().getTime();
var total=0;
$('select.category').each(function(){
var name=$(this).attr('id');
var option=$(this).find('option:selected').val();
total+=parseInt(option);
arguments[name]=option;
});
The 'total' variable works as expected. The the 'arguments' variable doesn't. Almost like
a variable scope issue or something. If I put some extra debug code to print out all the
property/value pairs, outside each loop I only see original four, and inside each loop only
the new one just set and none of the original four.?
I am currently encountering a problem with setting "display" property from "none" to "block":
Browsers will refresh itself when the display property is changed; this causes the element to display then suddenly disappear after the page reload. Do you guys have an idea what I can do to avoid it?
I tried using jquery's show command, css command with setting display to block, and pure javascript method like document.getElementById("theId").style.display="block".
all object oriented langs give a posibility to implement many construstors
can I have few constructors in js
i.e.:
function X()
{
this.Id = 1;
}
function X(id)
{
this.Id = id;
}
X.prototype.print = function()
{
alert( 'Id: '+this.Id );
}
var x1 = new X();
var x2 = new X(5);
it doesn't work, print return:
for x1: Id: undefined
for x2: Id: 5
my task was to make two constructors for the code that I also posted and they are not working. why they are not working. I posted them right below. here are my constructors for course and Faculty
course.js:
function Course (name, times, instructorName, instructorDept ) {
this.name = name ||"unknown course name";
this.times = times||"unknown time";
this.instructor = new Faculty(instructorName, instructorDept);
[Code]....
I'm trying to understand how JS constructors work. In particular, I'm trying to work out how I can call a parameterised constructor and check that the values of the parameters are valid within an object that has private properties. So for test purposes, I construct a data of birth object like this:
HTML Code:
<pre>
function Dob( day, month, year ) {
[code]....
I wrote some prototype functions in my code for arrays this is one of them !
Array.prototype.inArray = function(value){
for (var x in this) {
if (this[x] === value) {
return true;
}
}
return false;
};
when I iterate through array .. I get this functions as values in array !!!
can anybody explain this !?!?
I'm having difficulty trying to return a multi-demensional array using Javascript Prototype's Hash Object.I have been able to return the values of the following associative php array using JSON and Javascript Prototype's Hash Object:
php array
$player = array(
'PlayerName' => 'Ron Artest',
'Position' => 'Forward',[code]............
I have a script that slideshows 5 images. Below the images is a numbered list; 1-5. I'd like to set the style of the number buttons based on the image being displayed as the images scroll from one to the next. Code:
View 3 Replies View RelatedI have a question about removing an item from an array.I am looking to remove an item from the array based on the property.Ie.arr = [{a1: 1, a2: 2},{a1: 3, a2: 4}, {a1: 5, a2: 6}]remove first item from array because a1 = 1.I am not entirely sure how to do this. I tried messing around withgrep a bit, but that didn't turn out well.
View 3 Replies View RelatedHow can I go about setting a number of variables using a table which will
have the variable names to be declared in one table. The data to be assigned
will reside in another. As an example, I know this assignment works:
var nam0 = tab[0]
var nam1 = tab[1]
var nam2 = tab[2]
..
..
..
What I would like is to use two tables
var namtab = ["nam0","nam1","nam2"]
var tab = ["va0","val1","val2"]
Then using a loop, assign the variables so that I may address them by name
"nam0" rather than namtab[0].
var nametab = ["nam0","nam1","nam2"] ** also tried w/o the quotes
for(var i=0;i<3;i++) {
var nametab[i] = crumbs[0];
I am a newbie and am writing a function. I want the function to refer to an arrays elements to get the biggest, but I dont know how to do this.
Here is the code:
what I am trying to do, is get the array elements to be called and give me an answer. Will I need to add the array to the function? It is further down the code after the function at the moment. Or will I need to add the array elements to the function?
I have an array form input with an id: field[0], field[1] etc.How can I set the value of each array element directly?
$("#field[0]").val("value") doesn't appear to work.
I have part of a script like so:
var audioPlaylist = new Playlist("2", [
{
mp3:"audio/eight-day-week.m4a"
[code]....
I am trying to use the sortBy function in the prototype.js
library. Nevertheless, I can't work out what to include in the iterator
function. Can someone shed some light on this?