I'm trying to create a calculator out of javascript to work on my skills. I've added the class num to all of my buttons that have a number.
I'm trying to display to display the innerHTML of those buttons in the console when I click them with this code:
var num = document.getElementsByClassName('num');
num.addEventListener('click', getNum);
function getNum(){
console.log(num.innerHTML);
}
getNum();
However all I get is
num.addEventListener is not a function.
Here is my codepen: https://codepen.io/teenicarus/pen/wrEzwd
what could I be doing wrong?
You need to change the code like below. getElementsByClassName returns collection of elements. Loop through the elements and add click event listener. In getNum, you can use this to get access to the button clicked.
var num = document.getElementsByClassName('num');
for (var i = 0; i < num.length; i++) {
num[i].addEventListener('click', getNum);
}
function getNum(){
console.log(this.innerHTML);
}
You can also use Array forEach like the following:
[].forEach.call(num, function(el){
el.addEventListener('click', getNum);
})
getElementsByClassName returns a collection of elements, not a single element. If you want to get single element assign it an id attribute and use getElementById. This way you can use addEventListener function
Here's a solution you can plug directly in your codepen:
var nums = document.getElementsByClassName('num');
[].forEach.call(nums, num => num.addEventListener('click', numClick));
function numClick(){
// adding + turns the text into an actual number
console.log(+this.innerHTML);
}
getElementsByClassName() returns an HTMLCollection, to iterate over it you can pass it to [].forEach.call() like I showed above.
I also renamed the handler to numClick, since it doesn't "get" the number. And added +, which is a nice shortcut to turn text into a number (otherwise, adding two numbers would yield unexpected results, like "1" + "2" => "12"
The .getElementsByClassName returns not an element, but a collection of them.
You can access elements using .getElementsByClassName(num)[element's sequential number], or better use id's and getElementById method.
Here is the modified code for your desired output.just copy and try:
var num = document.getElementsByClassName('num');
//num.addEventListener('click', getNum);
for (var i = 0; i < num.length; i++) {
num[i].addEventListener('click', getNum);
}
function getNum(){
document.getElementById('result').innerHTML+=this.innerHTML;
console.log('value:'+this.innerHTML);
}
//getNum();
As you tagged Jquery to your question I suppose that you are able to use Jquery as well. You can grab the clicked element's class and referance it with 'this' to get its text.
$('.num').click(function(){
var x = $(this).text();
console.log(x);
});
This is a working example you can check the console.log DEMO
The context:
I need to get some dynamic ids that are inside a TD element, to pass it as a parameter and call an specific function.
I added a class (.calcStartPrice) to the TD, so that it helps me iterating inside its elements:
var inputEl, eventStartPrice, exchangeRate, convertedStartPriceEl, currSymbol, decimalPlaces;
jQuery(".calcStartPrice").each(function (i,e) {
jQuery(e).find('span, input').each(function (a,b) {
console.info(b.id);
});
});
When I run this code, I have the following ids:
eventStartPrice_S20_L10140
S20_L10140_startPrice
exchangeRate_S20_L10140
curSymbol_S20_L10140
decPlaces_S20_L10140
converted_StartPrice_S20_L10140
Now, what I want to do is to check whether the id starts with eventStartPrice, for example, so that I'll attribute the id to a variable.
What I tried:
var eventStartPrice;
jQuery(".calcStartPrice").each(function (i,e) {
jQuery(e).find('span, input').each(function (a,b) {
//console.info(b.id);
if (jQuery(b[id^="eventStartPrice"])) { //this is wrong!!!
eventStartPrice = b.id;
console.info(eventStartPrice);
}
});
});
But it didn't work...
How can I check inside that second iteration if the id starts with some string?
Replace :
if (jQuery(b[id^="eventStartPrice"])) { //this is wrong!!!
With :
if (/^eventStartPrice/.test(b.id)) {
You can use regexp :
if (b.id.match(/^eventStartPrice/)))
Try this:
$(b).is("[id^='eventStartPrice']")
basically, b is not a normal object, you need to wrap it into a jQuery object so that you can perform operations on it. Or, more accurately, you're trying to access b as a jQuery object when it isn't.
Use the jquery split method
id_val = b.id
name = id_val.split('_');
Now name[0] will contain characters before '_'.
You can easily compare it using if statement
if(name[0] == "eventStartPrice")
{
......
}
When u use jQuery each u get the dom element as this. If u then create a jQuery object of that u can apply all the magic to it. Thats what ur missing in ur code. So here is my sugestion how to rewrite ur function.
var eventStartPrice;
jQuery(".calcStartPrice").each(function (i,e) {
jQuery(e).find('span, input').each(function (a,b) {
var $this = jQuery(this);
if ($this.is("[id^=eventStartPrice]")) {
eventStartPrice = $this.attr("id");
console.info(eventStartPrice);
}
});
});
U can test it out in this fiddle
I want to ask what is the best way to search string and get matched element?
//I want to get similar or matched element and the index of it.
//Search key ward
var key = 'Pap';
<ul>
<li>Papa</li>
<li>Mama</li>
</ul>
My Idea now is use $.each and match its text of each, but I believe that should be a wrong way. However, I couldn't find any references from net about this question.
Thank you very much.
Use :contains selector
$('*:contains("'+key+'"):last')
To find exact match will the whole text in element use this
$.fn.exactMatch = function (key) {
var p = $(this).find(':contains("' + key + '"):last');
if (p.text() == key) {
p.css('background', 'yellow');
} else {
//Not exact match function if wanted
}
}
To use this function do this
$(el).exactMatch(key);
doStuff(document.getElementById("myCircle1" "myCircle2" "myCircle3" "myCircle4"));
This doesn't work, so do I need a comma or semi-colon to make this work?
document.getElementById() only supports one name at a time and only returns a single node not an array of nodes. You have several different options:
You could implement your own function that takes multiple ids and returns multiple elements.
You could use document.querySelectorAll() that allows you to specify multiple ids in a CSS selector string .
You could put a common class names on all those nodes and use document.getElementsByClassName() with a single class name.
Examples of each option:
doStuff(document.querySelectorAll("#myCircle1, #myCircle2, #myCircle3, #myCircle4"));
or:
// put a common class on each object
doStuff(document.getElementsByClassName("circles"));
or:
function getElementsById(ids) {
var idList = ids.split(" ");
var results = [], item;
for (var i = 0; i < idList.length; i++) {
item = document.getElementById(idList[i]);
if (item) {
results.push(item);
}
}
return(results);
}
doStuff(getElementsById("myCircle1 myCircle2 myCircle3 myCircle4"));
This will not work, getElementById will query only one element by time.
You can use document.querySelectorAll("#myCircle1, #myCircle2") for querying more then one element.
ES6 or newer
With the new version of the JavaScript, you can also convert the results into an array to easily transverse it.
Example:
const elementsList = document.querySelectorAll("#myCircle1, #myCircle2");
const elementsArray = [...elementsList];
// Now you can use cool array prototypes
elementsArray.forEach(element => {
console.log(element);
});
How to query a list of IDs in ES6
Another easy way if you have an array of IDs is to use the language to build your query, example:
const ids = ['myCircle1', 'myCircle2', 'myCircle3'];
const elements = document.querySelectorAll(ids.map(id => `#${id}`).join(', '));
No, it won't work.
document.getElementById() method accepts only one argument.
However, you may always set classes to the elements and use getElementsByClassName() instead. Another option for modern browsers is to use querySelectorAll() method:
document.querySelectorAll("#myCircle1, #myCircle2, #myCircle3, #myCircle4");
I suggest using ES5 array methods:
["myCircle1","myCircle2","myCircle3","myCircle4"] // Array of IDs
.map(document.getElementById, document) // Array of elements
.forEach(doStuff);
Then doStuff will be called once for each element, and will receive 3 arguments: the element, the index of the element inside the array of elements, and the array of elements.
getElementByID is exactly that - get an element by id.
Maybe you want to give those elements a circle class and getElementsByClassName
document.getElementById() only takes one argument. You can give them a class name and use getElementsByClassName() .
Dunno if something like this works in js, in PHP and Python which i use quite often it is possible.
Maybe just use for loop like:
function doStuff(){
for(i=1; i<=4; i++){
var i = document.getElementById("myCiricle"+i);
}
}
Vulgo has the right idea on this thread. I believe his solution is the easiest of the bunch, although his answer could have been a little more in-depth. Here is something that worked for me. I have provided an example.
<h1 id="hello1">Hello World</h1>
<h2 id="hello2">Random</h2>
<button id="click">Click To Hide</button>
<script>
document.getElementById('click').addEventListener('click', function(){
doStuff();
});
function doStuff() {
for(var i=1; i<=2; i++){
var el = document.getElementById("hello" + i);
el.style.display = 'none';
}
}
</script>
Obviously just change the integers in the for loop to account for however many elements you are targeting, which in this example was 2.
The best way to do it, is to define a function, and pass it a parameter of the ID's name that you want to grab from the DOM, then every time you want to grab an ID and store it inside an array, then you can call the function
<p id="testing">Demo test!</p>
function grabbingId(element){
var storeId = document.getElementById(element);
return storeId;
}
grabbingId("testing").syle.color = "red";
You can use something like this whit array and for loop.
<p id='fisrt'>??????</p>
<p id='second'>??????</p>
<p id='third'>??????</p>
<p id='forth'>??????</p>
<p id='fifth'>??????</p>
<button id="change" onclick="changeColor()">color red</button>
<script>
var ids = ['fisrt','second','third','forth','fifth'];
function changeColor() {
for (var i = 0; i < ids.length; i++) {
document.getElementById(ids[i]).style.color='red';
}
}
</script>
For me worked flawles something like this
doStuff(
document.getElementById("myCircle1") ,
document.getElementById("myCircle2") ,
document.getElementById("myCircle3") ,
document.getElementById("myCircle4")
);
Use jQuery or similar to get access to the collection of elements in only one sentence. Of course, you need to put something like this in your html's "head" section:
<script type='text/javascript' src='url/to/my/jquery.1.xx.yy.js' ...>
So here is the magic:
.- First of all let's supose that you have some divs with IDs as you wrote, i.e.,
...some html...
<div id='MyCircle1'>some_inner_html_tags</div>
...more html...
<div id='MyCircle2'>more_html_tags_here</div>
...blabla...
<div id='MyCircleN'>more_and_more_tags_again</div>
...zzz...
.- With this 'spell' jQuery will return a collection of objects representing all div elements with IDs containing the entire string "myCircle" anywhere:
$("div[id*='myCircle']")
This is all! Note that you get rid of details like the numeric suffix, that you can manipulate all the divs in a single sentence, animate them... Voilá!
$("div[id*='myCircle']").addClass("myCircleDivClass").hide().fadeIn(1000);
Prove this in your browser's script console (press F12) right now!
As stated by jfriend00,
document.getElementById() only supports one name at a time and only returns a single node not an array of nodes.
However, here's some example code I created which you can give one or a comma separated list of id's. It will give you one or many elements in an array. If there are any errors, it will return an array with an Error as the only entry.
function safelyGetElementsByIds(ids){
if(typeof ids !== 'string') return new Error('ids must be a comma seperated string of ids or a single id string');
ids = ids.split(",");
let elements = [];
for(let i=0, len = ids.length; i<len; i++){
const currId = ids[i];
const currElement = (document.getElementById(currId) || new Error(currId + ' is not an HTML Element'));
if(currElement instanceof Error) return [currElement];
elements.push(currElement);
};
return elements;
}
safelyGetElementsByIds('realId1'); //returns [<HTML Element>]
safelyGetElementsByIds('fakeId1'); //returns [Error : fakeId1 is not an HTML Element]
safelyGetElementsByIds('realId1', 'realId2', 'realId3'); //returns [<HTML Element>,<HTML Element>,<HTML Element>]
safelyGetElementsByIds('realId1', 'realId2', 'fakeId3'); //returns [Error : fakeId3 is not an HTML Element]
If, like me, you want to create an or-like construction, where either of the elements is available on the page, you could use querySelector. querySelector tries locating the first id in the list, and if it can't be found continues to the next until it finds an element.
The difference with querySelectorAll is that it only finds a single element, so looping is not necessary.
document.querySelector('#myCircle1, #myCircle2, #myCircle3, #myCircle4');
here is the solution
if (
document.getElementById('73536573').value != '' &&
document.getElementById('1081743273').value != '' &&
document.getElementById('357118391').value != '' &&
document.getElementById('1238321094').value != '' &&
document.getElementById('1118122010').value != ''
) {
code
}
You can do it with document.getElementByID Here is how.
function dostuff (var here) {
if(add statment here) {
document.getElementById('First ID'));
document.getElementById('Second ID'));
}
}
There you go! xD
I found another similar question about this with a solution but it didn't work for me. I am new to jquery so thanks in advance for helping me solve my noobie question.
I am trying to use a variable for the class name. So that I can loop through the right fields based on this variable. My variable returns .reqfields4 but I get this error Error: Syntax error, unrecognized expression: ", if I enter the value manually, it works.
How can I achieve this? Thanks.
var reqsection='\".reqfields4\"';
$(".reqfields4").each ( function() {
//$(reqsection).each ( function() {
if(( $(this).val())==''){
some code...
}
else{
some code...
}
});
Just change var reqsection='\".reqfields4\"'; to var reqsection='.reqfields4'; - you don't need the inner string quotes.
You don't need quotes inside the value of the variable:
var reqsection = '.reqfields4';
$(reqsection).each( ... );
If you have a class name — just a class name — you can add the .:
var reqsection = 'reqfields4';
$('.' + reqsection).each( ... )
You can try like follows,
var reqsection=".reqfields4";
$(reqsection).each ( function() {
if(( $(this).val())==''){
some code...
}
else{
some code...
}
});
If you say var reqsection= '\".reqfields4\"';
then
$(reqsection).each( function() {});
Consider it like like you told jQuery this:
$(' ".reqfields4" ').each( function() {});
In other words you said: [ Please select now ".reqfields4" including the quotemarks ]. All class selectors must start with dot(.), but you just started your jQuery selector with a quotemark (") so of course it won't work at all (it won't try to select any classes, of course), and probably would throw an error from jQuery - I don't think ANY jQuery selector string can have quotemark(") as the actual first character of the selector!.
If you do this instead:
var reqsection= ".reqfields4";
$(".reqfields4").each( function() {});
$(reqsection).each( function() {});
The above two lines are equivalent.