I have a function in my header to adjust the size of an iframe and I call it in the footer for both window.onload and window.onresize.
var resize = function(elementId) {
document.getElementById(elementId).height = parseInt(document.getElementById(elementId).offsetWidth)*0.63;
};
onload works:
window.onload = resize("youtube");
onresize does not:
window.onresize = resize("youtube")
Forgive me if I'm doing anything wrong with my javascript. I'm still kind of new to it.
You are executing the function right away instead of returning a function.
So if you log what window.onload contains, it would contain undefined
You need to return a function (also you might want to cache the element, like I did):
var resize = function(elementId) {
return function(){
var element = document.getElementById(elementId);
element.height = parseInt(element.offsetWidth) * 0.63;
};
};
What the above does still allows for you to do:
window.onload = resize("youtube");
Since resize now returns a callback window.onload (in theory) is now the same as:
window.onload = function(){
var element = document.getElementById("youtube");
element.height = parseInt(element.offsetWidth) * 0.63;
};
window.onresize (and window.onload for that matter) should be a function reference;
window.onresize = function () {
resize('youtube')
}
Your implementation will execute the functions and assign the return value to the window properties.
Related
I have read countless of answers of this issue and I came up with the following, but it doesn't work either.
function fitToParent(objsParent, tagName) {
var parent, imgs, imgsCant, a, loadImg;
//Select images
parent = document.getElementById(objsParent);
imgs = parent.getElementsByTagName(tagName);
imgsCant = imgs.length;
function scaleImgs(a) {
"use strict";
var w, h, ratioI, wP, hP, ratioP, imgsParent;
//Get image dimensions
w = imgs[a].naturalWidth;
h = imgs[a].naturalHeight;
ratioI = w / h;
//Get parent dimensions
imgsParent = imgs[a].parentNode;
wP = imgsParent.clientWidth;
hP = imgsParent.clientHeight;
ratioP = wP / hP;
//I left this as a test, all this returns 0 and false, and they shouldn't be
console.log(w);
console.log(h);
console.log(ratioI);
console.log(imgs[a].complete);
if (ratioP > ratioI) {
imgs[a].style.width = "100%";
} else {
imgs[a].style.height = "100%";
}
}
//Loop through images and resize them
var imgCache = [];
for (a = 0; a < imgsCant; a += 1) {
imgCache[a] = new Image();
imgCache[a].onload = function () {
scaleImgs(a);
//Another test, this returns empty, for some reason the function fires before aplying a src to imgCache
console.log(imgCache[a].src);
}(a);
imgCache[a].src = imgs[a].getAttribute('src');
}
}
fitToParent("noticias", "img");
To summarise, the problem is the event onload triggers before the images are loaded (or that is how I understand it).
Another things to add:
I don't know at first the dimensions of the parent nor the child,
because they varied depending of their position on the page.
I don't want to use jQuery.
I tried with another function, changing the onload event to
window, and it worked, but it takes a lot of time to resize because
it waits for everything to load, making the page appear slower,
that's how I came to the conclusion the problem has something to do
with the onload event.
EDIT:
I made a fiddle, easier to look at the problem this way
https://jsfiddle.net/whn5cycf/
for some reason the function fires before aplying a src to imgCache
Well, the reason is that you are calling the function immedeatly:
imgCache[a].onload = function () {
}(a);
// ^^^ calls the function
You call the function and assign undefined (the return value of that function) to .onload.
If you want to use an IIFE to capture the current value of a, you have to make it return a function and accept a parameter to which the current value of a is assigned to:
imgCache[a].onload = function (a) {
return function() {
scaleImgs(a);
};
}(a);
Have a look again at JavaScript closure inside loops – simple practical example .
in my scriptfile.js I layout a simple text re-sizing function. On its own, the function works as expected. However, when I try to add $(window).resize(fitheadliner()); to my scriptfile to fire the the fitheadliner() function on the resize event, it get a "Uncaught ReferenceError: fitheadliner is not defined" error. I have moved the resize function around the scriptfile thinking it may be a scope issue to no avail. Here is the contents of the file:
( function( $ ) {
$.fn.fitheadliner = function() {
this.each(function() {
var
$headline = $(this),
$parent = $headline.parent();
var
textW = $headline.width(),
parentW = $parent.width(),
ratio = parentW / textW;
var
originalSize = parseFloat($headline.css('font-size')),
newSize = originalSize * (0.9 * ratio);
$headline.css("font-size", newSize);
});
};
$(window).resize(fitheadliner());
} )( jQuery );
Here:
$.fn.fitheadliner = …
fitheadliner is defined as a property of $.fn.
But here:
$(window).resize(fitheadliner());
you are attempting to access it as a variable (and call it). Consider:
(function($) {
function fitheadliner() {
...
}
// Assign a reference, don't call the function
$(window).resize(fitheadliner);
}(jQuery));
However, you have a further issue from:
this.each(function() {
The function is called with window as this, and window doesn't have an each method. I don't understand how you aren't seeing other errors (or erroneous behaviour). Perhaps this should be replaced with a selector:
$(<selector>).each(...);
It's not quite a scoping issue. More like a qualification issue.
When this line executes
$(window).resize(fitheadliner());
You are saying, run $(window), then run fitheadliner(), then run the .resize method of the return value of the first call, passing it the return value of the first function call.
It's easy to think that the manner in which you are calling fitheadliner() would tie it to the $ object, but it doesn't. There's no reason it would. Each expression is evaluated independently and then chained appropriately.
Therefore, this expression is looking for a symbol in scope named fitheadliner that must be of type function. There are no symbols in scope with that name. There is, however, a symbol named $.fn.fitheadliner
To get past this error, you need to fully-qualify the reference, like
$(window).resize($.fn.fitheadliner());
But the fact is, I don't think that is totally what you want either. .resize takes a handler function. fitheadliner does not return a function, or return anything. It actually does some work. So I think what you meant to do was to pass a reference to fitheadliner to resize.
That's easy - take the paranthesis out.
$(window).resize($.fn.fitheadliner);
Now, even better, there is probably no reason to attach fitheadliner to the jQuery prototype like that. Try this. It may more closer to what you were trying to do.
( function( $ ) {
function fitheadliner() {
this.each(function() {
var
$parent = $(this).parent(),
$headline = $(this);
var
textW = $(this).width(),
parentW = $parent.width(),
ratio = parentW / textW;
var
originalSize = parseFloat($(this).css('font-size')),
newSize = originalSize * (0.9 * ratio);
$(this).css("font-size", newSize);
});
}
$(window).resize(fitheadliner);
} )( jQuery );
This defines a function in scope called fitheadliner and then passes a reference to it to resize.
Personally, I would take it one step further and inline the function anonymously since it does not need to be reused. But it's a matter of form/preference for me. There's semantically no difference.
( function( $ ) {
$(window).resize(function fitheadliner() {
this.each(function() {
var
$parent = $(this).parent(),
$headline = $(this);
var
textW = $(this).width(),
parentW = $parent.width(),
ratio = parentW / textW;
var
originalSize = parseFloat($(this).css('font-size')),
newSize = originalSize * (0.9 * ratio);
$(this).css("font-size", newSize);
});
});
} )( jQuery );
var fbToggle = document.getElementById("fbToggle");
and later in the script
fbToggle.addEventListener("click", toggle("fbContainer"));
Console tells me that fbToggle is NULL
This is in the document though.
<input type="checkbox" id="fbToggle">
I wasnt using eventListener before, so maybe there is a special order of declaration i'm missing ?
EDIT :
entire js :
function toggle(target) {
var obj = document.getElementById(target);
display = obj.style.display;
if (display == "none") {display = "block"}
else {display = "none"}
}
function init() {
var fbToggle = document.getElementById("fbToggle");
var twitToggle = document.getElementById("twitToggle");
var pinToggle = document.getElementById("pinToggle");
console.log(fbToggle); // NULL
fbToggle.addEventListener("click", toggle("fbContainer"));
twitToggle.addEventListener("click", toggle("twitContainer"));
pinToggle.addEventListener("click", toggle("pinContainer"));
}
window.onload = init();
HTML is way too long.but JS is in head, called from external file. Also i'm not in quirk mode.
It is not clear where "later in the script" is. If it is in different scope definitely it is not going to work. Suggesting you to keep everything in a global object if possible so that you can access from different places in the script.
window.globals = {};
window.globals.fbToggle = document.getElementById("fbToggle");
window.globals.fbToggle.addEventListener("click", function () {
toggle("fbContainer")
});
function toggle(container) {
alert(container);
}
http://jsfiddle.net/ST938/
Another point is addEventListener expects a function or function idenitifier, NOT a function call.
addEventListener("click", toggle("fbContainer")); // wrong
addEventListener("click", toggle); // correct
So if you want to pass a parameter
window.globals.fbToggle.addEventListener("click", function () {
toggle("fbContainer")
});
function toggle(container) {
alert(container);
}
In JavaScript, putting brackets after a function name causes it to be called. If you want to reference a function without calling it you must not put brackets after the name:
window.onload = init(); // this calls init() immediately
window.onload = init; // this correctly stores init in window.onload
The same applies to toggle(). If you need to pre-specify some of the arguments you can wrap it in an anonymous function:
fbToggle.addEventListener("click", function() { toggle("fbContainer"); });
or you can use bind:
fbToggle.addEventListener("click", toggle.bind(null, "fbContainer"));
I have read all the other similar posts but I don't understand why it I have this problem.
I have a canvas (#canvas) and an image (hero.png) on the page, and a JS file loaded at the end of the body. In the JS code...
This works:
var game = {};
game.canvas = document.getElementById('canvas');
game.ctx = game.canvas.getContext("2d");
game.draw = function(){
game.ctx.drawImage(game.hero, 200, 200);
}
game.hero = new Image();
game.hero.src = "hero.png";
game.hero.onload = game.draw;
And this doesn't work:
var game = {};
game.canvas = document.getElementById('canvas');
game.ctx = game.canvas.getContext("2d");
game.hero = new Image();
game.hero.src = "hero.png";
game.hero.onload = game.draw;
game.draw = function(){
game.ctx.drawImage(game.hero, 200, 200);
}
Nothing appears. No error in the console. Why???
Thanks!
You can call functions before define them only with this syntax:
function draw()
{
//COde here
}
By writting
game.draw = function(){};
You define a method to your object, you don't define a JavaScript function: that's why you can't call it before define it :)
In your second hunk of code, you're defining
game.hero.onload = game.draw;
When game.draw is undefined, so your onload is undefined and nothing happens when the image is done loading.
game.draw is not set when you assign it in your second example, you are copying an undefined value into hero.onload.
One workaround is to wrap the function you want to call in an anonymous function and call yours from there:
game.hero.onload = function(){ game.draw(); };
Have in mind that if hero loads before the definition of game.draw is finished, this code will fail.
There are many topics related to my question and i have been through most of them, but i haven't got it right. The closest post to my question is the following:
How to call functions that are nested inside a JQuery Plugin?
Below is the jquery plugin i am using. On resize, the element sizes are recalculated. I am now trying to call the function resizeBind() from outside of the jquery plugin and it gives me error
I tried the following combinations to call the function
$.fn.splitter().resizeBind()
$.fn.splitter.resizeBind()
Any ideas, where i am getting wrong?
;(function($){
$.fn.splitter = function(args){
//Other functions ......
$(window).bind("resize", function(){
resizeBind();
});
function resizeBind(){
var top = splitter.offset().top;
var wh = $(window).height();
var ww = $(window).width();
var sh = 0; // scrollbar height
if (ww <0 && !jQuery.browser.msie )
sh = 17;
var footer = parseInt($("#footer").css("height")) || 26;
splitter.css("height", wh-top-footer-sh+"px");
$("#tabsRight").css("height", splitter.height()-30+"px");
$(".contentTabs").css("height", splitter.height()-70+"px");
}
return this.each(function() {
});
};
})(jQuery);
I had the same problem. Those answers on related posts didn't work for my case either. I solved it in a round about way using events.
The example below demonstrates calling a function that multiplies three internal data values by a given multiplier, and returns the result. To call the function, you trigger an event. The handler in turn triggers another event that contains the result. You need to set up a listener for the result event.
Here's the plugin - mostly standard jQuery plugin architecture created by an online wizard:
(function($){
$.foo = function(el, options){
// To avoid scope issues, use 'base' instead of 'this'
var base = this;
// Access to jQuery and DOM versions of element
base.$el = $(el);
base.el = el;
// Add a reverse reference to the DOM object
base.$el.data("foo", base);
base.init = function(){
base.options = $.extend({},$.foo.defaultOptions, options);
// create private data and copy in the options hash
base.private_obj = {};
base.private_obj.value1 = (base.options.opt1);
base.private_obj.value2 = (base.options.opt2);
base.private_obj.value3 = (base.options.opt3);
// make a little element to dump the results into
var ui_element = $('<p>').attr("id","my_paragraph").html(base.private_obj.value1 +" "+ base.private_obj.value2+" " +base.private_obj.value3);
base.$el.append(ui_element);
// this is the handler for the 'get_multiplied_data_please' event.
base.$el.bind('get_multiplied_data_please', function(e,mult) {
bar = {};
bar.v1 = base.private_obj.value1 *mult;
bar.v2 = base.private_obj.value2 *mult;
bar.v3 = base.private_obj.value3 *mult;
base.$el.trigger("here_is_the_multiplied_data", bar);
});
};
base.init();
}
$.foo.defaultOptions = {
opt1: 150,
opt2: 30,
opt3: 100
};
$.fn.foo = function(options){
return this.each(function(){
(new $.foo(this, options));
});
};
})(jQuery);
So, you can attach the object to an element as usual when the document is ready. And at the same time set up a handler for the result event.
$(document).ready(function(){
$('body').foo();
$('body').live('here_is_the_multiplied_data', function(e, data){
console.log("val1:" +data.v1);
console.log("val2:" +data.v2);
console.log("val3:" +data.v3);
$("#my_paragraph").html(data.v1 +" "+ data.v2+" " +data.v3);
});
})
All that's left is to trigger the event and pass it a multiplier value
You could type this into the console - or trigger it from a button that picks out the multiplier from another UI element
$('body').trigger('get_multiplied_data_please', 7);
Disclaimer ;) - I'm quite new to jQuery - sorry if this is using a hammer to crack a nut.
resizeBind function is defined as private so you cannot access it from outside of it's scope. If you want to use it in other scopes you need to define it like that
$.fn.resizeBind = function() { ... }
Then you would call it like that $(selector').resizeBind()
You have defined the resizeBind function in a scope that is different from the global scope. If you dont'use another javascript framework or anything else that uses the $ function (to prevent conflict) you can delete the
(function($){
...
})(jQuery);
statement and in this way the function will be callable everywhere without errors
I didn't test it:
this.resizeBind = function() { .... }