I'm trying to replicate jQuery's element manipulation to a certain extent. Now what I have found to be very useful is the .first() selector. I would like to be able to chain functions like this;
getElement(selector).first().hasClass(className);
Now, there are 2 issues with how far I've gotten (Do note that my code example is minimised, so please, no comments about error-handling.)
var getElement = function(selector, parent) {
ret = document.querySelectorAll(selector);
this.element = ret;
this.hasClass = function(className) {
className.replace('.', '');
if(this.multiple())
{
console.log('Cannot use hasClass function on multiple elements');
return false;
}
};
this.first = function() {
this.element = this.element[0];
return this;
};
return this;
};
My current problem
If I call my function;
var $test = getElement('.something');
//result: nodelist with .something divs
If I call for the first element within the result;
$test.first();
//Result: First div, perfect!
However, now if I call $test again, it will replace the elements property with the result of first(), meaning I have "lost" my old values. I don't want to lose them, I only want the first() functions for that specific functionality. Then I want $test to return all elements again.
Also, recalling first() will now end up undefined, since there is only 1 element left within this as it has deleted the old elements from within the object.
Another attempt
Now, I've also tried to turn it around a bit by returning the first-child instead of the entire class object;
this.first = function() {
return this.element[0];
};
However, I will
$test.first().hasClass(className);
//Returns ERROR, method hasClass undefined
this is because .hasClass exists on the original this, which doesn't get returned anymore since I'm now returning the element.
I have tried to get something out of jQuery's library, though that just confused me more...
I have googled this subject, but with all the 'chaining methods' solutions I'm finding, all of them seem to be overwriting the original values of the object, which is not what I want to happen. One other solution actually required me to re-initiate the object over and over again, which did not seem very efficient to me... Any help is appreciated. I'm assuming I'm going about this completely the wrong way.
-- If you can help me, please do explain why your solution works. I really feel like if I understand this, my understanding of javascript can expand a lot further. I just need to get past this structural(?) issue.
A method like first() should not modify this, it should create a new object and return that. You only use return this; in methods that modify an element rather than returning information derived from the element.
this.first = function() {
return new getElement(this.element[0]);
};
And note that you have to use new getElement to create an object, not just getElement.
This also requires a change to the constructor, so it can accept either a selector string or an element:
var getElement = function(selector, parent) {
var ret = typeof selector == "string" ? document.querySelectorAll(selector) : [selector];
...
}
You should also consider doing this in proper OO fashion, by putting the methods in a prototype, rather than defining them in every object.
var getElement = function(selector, parent) {
var ret = typeof selector == "string" ? document.querySelectorAll(selector) : [selector];
this.element = ret;
};
getElement.prototype.hasClass = function(className) {
className.replace('.', '');
if (this.multiple()) {
console.log('Cannot use hasClass function on multiple elements');
return false;
}
};
getElement.prototype.first = function() {
return new getElement(this.element[0])
};
this in your outer function refers to the window / global object.
Instead, return the ret variable itself.
In the inner functions (which become the object's methods), this acts the way you expect it to.
Here's an alternative solution, which allows chaining, even after you've called the first method:
var getElement = function(selector, parent) {
var ret = typeof selector == 'string' ? document.querySelectorAll(selector)
: selector;
ret.hasClass = function(className) {
if(!this.classList) {
console.log('Cannot use hasClass function on multiple elements');
return false;
} else {
return this.classList.contains(className);
}
};
ret.first = function() {
return new getElement(this[0]);
};
return ret;
};
console.log(getElement('p').length); //2
console.log(getElement('p').first().innerHTML); //abc
console.log(getElement('p').first().hasClass('test')); //true
console.log(getElement('p').first().hasClass('nope')); //fase
console.log(getElement('p').hasClass('test')); //false (multiple elements)
<p class="test">
abc
</p>
<p>
def
</p>
Here is how I would approach this:
Create a constructor, say Search, tasked to find the elements based on the input. Using a constructor is proper OO Programming and you also have the advantage of defining methods once in the prototype and they can be accessed by all instances.
Ensure that the context (this) is an array-like object, with numeric properties and a length, so that you can easily iterate over every matched element in the traditional way (using for loops, [].forEach etc).
Create a function, say getElement, that will use the constructor and return the result without having to use the new keyword all the time. Since the function returns an instance of our constructor, you can chain the methods you want as you would normally do.
The method first uses the constructor to create a new instance instead of modifying the original, since its role is to return the first element, not delete everything but the first element.
Each time you come up with a new method you want your object to have, you can simply add it to the prototype of the constructor.
Snippet:
;(function () {
function Search (value) {
var elements = [];
/* Check whether the value is a string or an HTML element. */
if (typeof value == "string") {
/* Save the selector to the context and use it to get the elements. */
this.selector = value;
elements = document.querySelectorAll(value);
}
else if (value instanceof Element) elements.push(value);
/* Give a length to the context. */
this.length = elements.length;
/* Iterate over every element and inject it to the context. */
for (var i = 0, l = this.length; i < l; i++) this[i] = elements[i];
}
/* The method that returns the first element in a Search instance. */
Object.defineProperty(Search.prototype, "first", {
value: function () {
return new Search(this[0]);
}
});
/* The global function that uses the Search constructor to fetch the elements. */
window.getElement = (value) => new Search(value);
/* Create a reference to the prototype of the constructor for easy access. */
window.getElement.fn = Search.prototype;
})();
/* Get all elements matching the class, the first one, and the first's plain form. */
console.log(getElement(".cls1"));
console.log(getElement(".cls1").first());
console.log(getElement(".cls1").first()[0]);
/* ----- CSS ----- */
.as-console-wrapper {
max-height: 100%!important;
}
<!----- HTML ----->
<div id = "a1" class = "cls1"></div>
<div id = "a2" class = "cls1"></div>
<div id = "a3" class = "cls1"></div>
Example:
In this example, I'm adding a new method called hasClass to the prototype of the constructor.
/* The method that returns whether the first element has a given class. */
Object.defineProperty(getElement.fn, "hasClass", {
value: function (value) {
return this[0].classList.contains(value);
}
});
/* Check whether the first element has the 'cls2' class. */
console.log(getElement(".cls1").first().hasClass("cls2"));
<!----- HTML ----->
<script src="//pastebin.com/raw/e0TM5aYC"></script>
<div id = "a1" class = "cls1 cls2"></div>
<div id = "a2" class = "cls1"></div>
<div id = "a3" class = "cls1"></div>
I think the easiest would be to return a new class that contains the nodes you have selected. That would be the easiest solution, as you don't really want to mutate any of your previous selectors.
I made a small example, using some ES6 that makes a few things easier to work with, which also has a $ to initiate the selections being made.
You would notice that first of all, any selection that is made, is just calling the native document.querySelectorAll but returns a new Node class. Both first and last methods also return those elements.
Lastly, hasClass should work on all elements in the current nodes selections, so it will iterate the current node, and check all classes in there, this one returns a simple bool, so you cannot continue with the method chaining there.
Any method you wish to chain, should either:
return this object (the current node)
return an element of the this object as a new node so any further manipulations can be done there
const $ = (function(global) {
class Node extends Array {
constructor( ...nodes ) {
super();
nodes.forEach( (node, key) => {
this[key] = node;
});
this.length = nodes.length;
}
first() {
return new Node( this[0] );
}
last() {
return new Node( this[this.length-1] );
}
hasClass( ...classes ) {
const set = classes.reduce( (current, cls) => {
current[cls] = true;
return current;
}, {} );
for (let el of this) {
for (let cls of el.classList) {
if (set[cls]) {
return true;
}
}
}
return false;
}
}
global.$ = function( selector ) {
return new Node( ...document.querySelectorAll( selector ) );
};
return global.$;
}(window));
let selector = $('.foo');
let first = selector.first(); // expect 1
console.log(first[0].innerHTML);
let last = selector.last();
console.log(last[0].innerHTML); // expect 4
console.log( first.hasClass('foo') ); // expect true
console.log( first.hasClass('bar') ); // expect false
console.log( selector.hasClass('foo') ); // expect true
console.log( selector.hasClass('bar') ); // expect true
<div class="foo">1</div>
<div class="foo">2</div>
<div class="foo bar">3</div>
<div class="foo">4</div>
You can update getElement so it returns back again when you send it an element.
var getElement = function(selector, parent) {
var ret = null
if (typeof selector === "string") {
ret = document.querySelectorAll(selector);
} else {
ret = selector
}
this.element = ret;
this.hasClass = function(className) {
className.replace('.', '');
if (this.multiple()) {
console.log('Cannot use hasClass function on multiple elements');
return false;
}
};
this.first = function() {
this.element = getElement(this.element[0]);
return this;
};
return this;
};
var test = getElement(".foo");
console.log(test.first())
console.log(test.first().hasClass)
<div class="foo">1</div>
<div class="foo">2</div>
<div class="foo">3</div>
<div class="foo">4</div>
You can use .querySelectorAll(), spread element and Array.prototype.find(), which returns the first match within an array or undefined
const getElement = (selector = "", {prop = "", value = "", first = false} = {}) => {
const el = [...document.querySelectorAll(selector)];
if (first) return el.find(({[prop]:match}) => match && match === value)
else return el;
};
let first = getElement("span", {prop: "className", value: "abc", first: true});
console.log(first);
let last = getElement("span");
console.log(all);
<span class="abc">123</span>
<span class="abc">456</span>
I am looking for a way to get all the attributes of an element that begins with "on" using jQuery or Vanilla JS. I am currently getting all attributes and then looping through them to get the ones I want using the method proposed by #primvdb on this post: Get all attributes of an element using jQuery.
My code looks like this:
/* Expanding .attr as proposed by #primvdb */
(function(old) {
$.fn.attr = function() {
if(arguments.length === 0) {
if(this.length === 0) {
return null;
}
var obj = {};
$.each(this[0].attributes, function() {
if(this.specified) {
obj[this.name] = this.value;
}
});
return obj;
}
return old.apply(this, arguments);
};
})($.fn.attr);
/* And then my function */
$.fn.attrThatBeginWith = function(begins){
var attributes = this.attr();
var attrThatBegin = {};
for(var attr in attributes){
if(attr.indexOf(begins)==0){
attrThatBegin[attr] = attributes[attr];
}
}
return attrThatBegin;
};
/* Usage */
var onAttributes = $("#MyElement").attrThatBeginWith("on");
And this works but is very "dirty". It's seems like with all the vast features of jQuery there should be a better "cleaner" way to do this. Does anybody have any suggestions?
You can get all attributes attached to an element with element.attributes.
The native attributes object can be converted to an array and then filtered based on the given string.
A plugin that does the above would look like
$.fn.attrThatBeginWith = function(begins){
return [].slice.call(this.get(0).attributes).filter(function(attr) {
return attr && attr.name && attr.name.indexOf(begins) === 0
});
};
FIDDLE
If I set a function under an object i can use it once only like
function handle(selector)
{
return{
elem:selector,
next:function(){
return (this.nextSibling.nodeType==1) ? this.nextSibling : this.nextSibling.nextSibling;
}
}
}
here i can say handle.next() this will work but if I want to say handle.next().next().next() my question is how I can use in this way as jquery does?
Speaking about your function you can modify it like this to make it work:
function handle(selector)
{
if (typeof selector === 'string') {
selector = document.querySelector(selector);
}
return{
elem:selector,
next:function(){
return handle(selector.nextElementSibling);
}
}
}
See jsfiddle.
UPD: Modified the code to support both elements and string selectors as a parameter.
UPD 2: Came out with an alternative variant. In this case we extend the native html element object and add new next method:
function handle(selector)
{
if (typeof selector === 'string') {
selector = document.querySelector(selector);
}
selector.next = function() {
return handle(selector.nextElementSibling);
};
return selector;
}
Fiddle is here.
I'm looking for the shortest syntax which could provide me the same result as this dojo line:
var divblock5 = dojo.create("div", {className: "barlittle", id: "block5"});
but I want to use plain JavaScript instead of dojo framework. I have a lot of dynamic element creation and I want to make my code short as possible.
var create = function(element, properties) {
var elmt = document.createElement(element);
for (var prop in properties) {
elmt[prop] = properties[prop];
}
return elmt;
}
create("div", {className: "barlittle", id: "block5"});
Or, my personal favorite that simply takes HTML and converts it to a DOM node :
var elmtify(html) {
var wrapper = document.createElement('div');
wrapper.innerHTML = html;
return wrapper.firstChild;
}
elmtify('<div class="barlittle" id="block5"></div>');
You should check put-selector: https://github.com/kriszyp/put-selector.
Since this seems to be a still open question I'm adding my method, which is almost the same as Tom said but my approach takes into account style information:
function createElement(tag, attrs) {
if(!tag) throw new SyntaxError("'tag' not defined"); // In case you forget
var ele = document.createElement(tag), attrName, styleName;
if(attrs) for(attrName in attrs) {
if(attrName === "style")
for(styleName in attrs.style) {ele.style[styleName] = attrs.style[styleName];}
else
ele[attrName] = attrs[attrName];
}
return ele;
}
So if you normally write, without any library:
var divBlock5 = document.createElement("div");
divBlock5.className = "barlittle";
divBlock5.id = "block5";
With the snippet Tom provided, you would just write:
var divBlock5 = createElement("div", {className:"barlittle", id:"block5"});
But say you want to add an independent style to your element. Then, with my addition, you write:
var divBlock5 = createElement("div", {className:"barlittle", id:"block5", style:{color:"#08A", fontWeight:"bold"}});
Hope this helps. Cheers!
function createElement(tag, attrs, html) {
if (!tag) throw new SyntaxError("'tag' not defined"); // In case you forget
var ele = document.createElement(tag),
attrName, styleName;
if (attrs)
for (attrName in attrs) {
if (attrName === "style")
for (styleName in attrs.style) { ele.style[styleName] = attrs.style[styleName]; }
else if (attrs[attrName])
ele.setAttribute(attrName, attrs[attrName]);
}
if (html)
ele.innerHTML = html;
return ele;
}
This solution builds on what Tom and Xch3l proposed, but it adds support for passing custom attributes to be applied to the DOM element. Which attributes exist as properties for any given DOM element depends on the DOM element's type, so using the element's setAttribute method is a more robust solution.
Note that you will need to pass a "class" attribute instead of "className," and that this solution also adds support for an optional HTML string that can be passed as the third parameter.
Here is an example of how to use the function:
var divBlock5 = createElement("div", {class:"barlittle", "data-my-custom-attribute":"lorem ipsum", id:"block5", style:{color:"#08A", fontWeight:"bold"}},`<h5>An Optional String of HTML to be Inserted Inside the Newly Created Element</h5><p>Preserve Line Spacing by Using Backticks Instead of Quotes</p>`);
createElement = function(type, className, id) {
var element = document.createElement(type);
element.className = className;
element.id = id;
return element;
}
I am relatively new to OOP so I am not sure about the terminology.
I have created a DOM element as a field of an object (eg myObject.myElement) and I appended the element to the document. The object has a .mousemove() event attached (using jQuery). I want to be able to select the object (myObject) for whom the selected element (myElement) is a field so that I can access other fields of the object. There is more than one object and the event handler is the same for elements of different objects. Is it possible to select the parent object of the element? Do I need to give the element the same fields so that I can access the same data?
I want to be able to do something like this but maybe it is not that straightforward:
$('.bubble').on({mousemove: function () {
parentObject = this.parentObject();
alert(parentObject.otherDataField);
});
The element was created like this:
function bubbleObject(value)
{
this.value = value;
this.element = document.createElement('div');
$(this.element).appendTo('.bubbles');
}
myFirstBubble = new bubbleObject(10);
mySecondBubble = new bubbleObject(100);
and I need to be able to access the value field for the object (I am making it simpler as the code is pretty long and mostly irrelevant to my issue).
Do I need to do this:
function bubbleObject(value)
{
this.value = value;
this.element = document.createElement('div');
$(this.element).appendTo('.bubbles');
this.element.value = value; // add same value to element
}
or is there a better way?
A back reference to the parent could be better than copying values:
function bubbleObject(value)
{
this.value = value;
this.element = document.createElement('div');
$(this.element).appendTo('.bubbles');
this.element.parent = this;
}
However, using this way you have to use element.parent.value instead.
Another approach (as I mentioned before) is to scan all element-containing objects if they contain a specific element. If you don't have all these objects in an array you have to scan all window components (as I said, this is expensive):
function findElement(element) {
for (obj in window) {
if (typeof obj === 'object' && obj.myElement == element) {
return obj;
}
}
return null;
}
This is just an untested draft. And it would be so much better if you have a list of parent objects which you can use instead of window.
function findElement(element) {
for (int i = 0, l = objList.length; i < l; i++) {
if (typeof objList[i] === 'object' && objList[i].myElement == element) {
return objList[i];
}
}
return null;
}