In the code below I`m checking if these 2 elements exist.
const var1 = form.elements[elemName1] ||
form.elements[elemName2]
if(var1){
doSmth
}
But what I need is to check if element's name contains a certain string.
Like:
const var1 = form.elements[NameContains(givenString)] ||
form.elements[NameContains(givenString)]
I tried to find the needed syntax in google bud did not succeeded.
You can use an attribute contains selector (*=) with querySelector (to find the first) or querySelectorAll (to get a list of matches).
For instance:
const var1 = form.querySelector("[name*=foo]");
finds the first element in form whose name attribute contains the substring foo. Similarly there's ^= for "starts with" and $= for "ends with."
If you're checking for two different substrings, either use a selector group:
const var1 = form.querySelector("[name*=foo], [name*=bar]");
or two calls:
const var1 = form.querySelector("[name*=foo]") || form.querySelector("[name*=bar]");
The difference between those is that the selector group will find the first matching element in document order, whether it's a foo or bar element. The second will look for a foo element first, and only look for a bar element if no foo is found.
Related
var tempid = document.getElementById("TDID1");
Using alert(JSON.stringify(tempid)) Gives
{"jQuery3600419938127216425761":{"events":{"click":[{"type":"click","origType":"click","data":null,"guid":14,"namespace":""}]}}}
When all i want it to give is a variable typeof sting with document.getElementById("TDID1")
JSON.stringify creates a string for the value you give it. When that value is an object, the string is JSON describing all of the own, enumerable properties of the object.
In your case, the object is a DOM element, and one on which jQuery has been used at some point.
When all i want it to give is a variable typeof sting with document.getElementById("TDID1")
If I understand you correctly, that's not what JSON.stringify is for. You could write the string directly of course:
const str = 'document.getElementById("TDID1")';
...but there's no way, starting from the value returned by getElementById, to construct a string for the way you accessed that value.
Or if you want the value of that element (assuming it's an input or select element), you could get that value from .value:
const value = document.getElementById("TDID1").value;
Or if you want the text content of a non-input element:
const text = document.getElementById("TDID1").textContent;
Or if you want the inner HTML of the element:
const html = document.getElementById("TDID1").innerHTML;
Or the outer HTML of the element:
const html = document.getElementById("TDID1").outerHTML;
I need to call either a array like below:
ONone = document.getElementById("'"+CB[x]+"'");
or a property value like so:
var ONone = document.getElementById("'"+animateSector.named.id+"'");
the above values i.e (CB[x] and animateSector.named.id) alert the value that i need however when there called in the
(document.getElementById("'"+CB[x]+"'")
and
(document.getElementById("'"+animateSector.named.id+"'")
they return a null console error saying
Onone is null
getElementById doesn't accept a CSS selector, it accepts an ID. So even if the id would need to be quoted in CSS, it doesn't matter, because this isn't CSS.
Without seeing your HTML it's impossible to be sure, but:
Get the element whose id is whatever is in CB[x], or whatever is in animateSector.named.id:
ONone = document.getElementById(CB[x]);
ONone = document.getElementById(animateSector.named.id);
Get the element whose id is CB[x]:
ONone = document.getElementById('CB[x]');
Get a list of elements whose name is CB[], and then get entry #x from that list:
list = document.querySelectorAll('[name="CB[]"]');
entryX = list[x];
querySelectorAll, as the name implies, does accept a CSS selector, and returns all matching elements in a list.
How to get number of element by id using javascript ?
http://jsfiddle.net/3AaAx/51/
normally, after load page , it's will alert 2 (length of element id ele1).
But why alert undefined
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<input type="text" id="ele1" class="test" value="test">
<input type="text" id="ele1" class="test" value="test">
<script>
$(function() {
//var xxx = document.getElementsByClassName('test');
var xxx = document.getElementById('ele1');
var xxx;
alert(xxx.length);
});
</script>
getElementById() returns just an element. A single element has no property length. (There may be exceptions, but in general ... Even if there is a length property it most likely does not refer to the amount of elements returned.)
You probably refer to the getElementsBy...() (note the s!) or querySelectorAll() functions, which return a NodeList, which has a length property.
This is how you get the number of elements returned by getElementById:
var xxx = (document.getElementById('ele1') === null) ? 0 : 1;
getElementById returns null if no element matched the id. If the function does not return null, then one and only one element matches the criteria. See more here.
The line you commented off is right:
//var xxx = document.getElementsByClassName('test');
getElementsByClassName returns a collection of DOM elements, which does have a length property. Note in this method Elements is plural form. length indicates the amount of elements in the collection.
However you misunderstand getElementById. This method will only return a DOM element (or null if there isn't such element). Note in this method Element is singular form. A DOM element doesn't have a length property usually.
Another problem in your code, ID should be unique within a page. If you have two or more elements with the same ID, that's illegal markup. In such case you will get unexpected result.
var sec = document.getElementsByName("secilenil")[0];
I did not understand the end of this statement which is [0].What does this mean? "secilenil" is the name of select element.
getElementsByName returns a NodeList of all elements with a name attribute equal to secilenil. Using [0] selects the first found node.
The [0] notation is similar to that of an array - it means you want to extract the element at the specific index.
MDN reference.
What is returned if $('#id') doesn't match anything? I figured it would be null or false or something similar so I tried checking like so:
var item = $('#item');
if (!item){
...
}
But that didn't work.
You can find how many elements were matched using:
$('selector').length
To check whether no elements were matched, use:
var item = $('#item');
if (item.length == 0) {
// ...
}
While $('selector').length is great for finding out how many objects your selector matches, its actually completely unnecesary. The thing about jQuery is that all selector based functions use length internally, so you could just do $(selector).hide() (or whatever) and it takes no action for an empty set.
A jQuery object that contains no DOM nodes.
You should be able to use
var item = $('#item');
if (!item[0]){
...
}
for your existence check.
An alias of the length attribute is the size() method. So you basically could also query:
$("selector").size()
to see how many elements are matched.