CODEWITHSUNDEEP
javascripthtmlcss-selectorsselectors-api
Berry Blue
Berry Blue

Reputation: 16482

Using querySelector with IDs that are numbers

From what I understand the HTML5 spec lets you use IDs that are numbers like this.

<div id="1"></div>
<div id="2"></div>

I can access these fine using getElementById but not with querySelector. If I try do the following I get SyntaxError: DOM Exception 12 in the console.

document.querySelector("#1")

I'm just curious why using numbers as IDs does not work querySelector when the HTML5 spec says these are valid. I tried multiple browsers.

Upvotes: 161

Views: 207556

Answers (9)

zwoolli
zwoolli

Reputation: 301

Based on the existing answers, I made this little helper function to do the job for me:

export function QueryID(id: string): string {
    // Declare and initialize variables
    let firstChar: string = id.charAt(0);
    let isnumber: boolean = !isNaN(parseInt(firstChar));
    let sliceId: string;
    
    // If first char is number, escape it
    if (isnumber) {
        firstChar = CSS.escape(firstChar);
        sliceId = id.slice(1);
        id = firstChar.concat(sliceId);
    }

    // Return id
    return `#${id}`.toString();
}

Upvotes: 0

Ronnie Smith
Ronnie Smith

Reputation: 18555

The CSS spec says:

In CSS, identifiers (including element names, classes, and IDs in selectors) can contain only the characters [a-zA-Z0-9] and ISO 10646 characters U+00A0 and higher, plus the hyphen (-) and the underscore (_); they cannot start with a digit, two hyphens, or a hyphen followed by a digit. Identifiers can also contain escaped characters and any ISO 10646 character as a numeric code (see next item). For instance, the identifier "B&W?" may be written as "B&W?" or "B\26 W\3F".

https://www.w3.org/TR/CSS2/syndata.html#characters

Upvotes: 0

Yash Narola
Yash Narola

Reputation: 107

Using CSS.escape(invalidID) is promising solution.

Solution Video: https://youtu.be/rH5IVJKmSOE

In Your Case: document.querySelector("#" + CSS.escape('1'))

OR

document.querySelector("[id='1']")

Upvotes: 1

Sonali Sharma
Sonali Sharma

Reputation: 31

To use dynamic Ids in the query selector have used simple code.

this.template.querySelector("[id='"+divId+"']");

If you are working on the iterations and want to access on id then checkout this code. I had iteration on accounts object and using clickable event on LWC:

<template for:each={accounts.data} for:item="acc">
     <div key={acc.Id} id={acc.Id} class="box" onclick={handleClick}>
       {acc.Name}
     </div>
</template>

I wanted to access div data with using its ID when calling the onclick event on the div.

handleClick(event){
 event.dataTransfer.setData("divId", event.target.id);
 var divId = event.dataTransfer.getData("divId");

 //Using the divId in querySelector       
 var Element = this.template.querySelector("[id='"+divId+"']");

}

Upvotes: 2

Per
Per

Reputation: 101

Here is a function I made just now for dealing with leading number ID's in CSS selectors, and it is IE safe as CSS.escape is not.

Pass the selector through this cleanSelector function before using it : 

var cleanSelector = function(selector){
    (selector.match(/(#[0-9][^\s:,]*)/g) || []).forEach(function(n){
        selector = selector.replace(n, '[id="' + n.replace("#", "") + '"]');
    });
    return selector;
};

var myselector = ".dog #980sada_as div span#aside:hover div.apple#05crab:nth-of-type(2), .ginger #2_green_div, div.cupcake #darwin p#23434-346365-53453";

var clean_myselector = cleanSelector(myselector);

// print to show difference
console.log(myselector);
console.log(clean_myselector);

//use the new selector like normal
var elems = document.querySelectorAll( clean_myselector );

Upvotes: 7

vikash Mishra
vikash Mishra

Reputation: 29

From the W3C documentation Attribute selectors syntax

Attribute values must be a valid CSS identifiers or String.

Thus, digits or alphanumeric strings with leading digit does not qualify as a valid identifier.

If you are using an ID generator utility for generating an identifier, you might end up with alpha numeric ids with leading digits.

A quick fix would be to either omit digits from the SEED of the generator( if it can be modified ) or always append a string to the id generated.

Upvotes: 3

Glavin001
Glavin001

Reputation: 1346

I needed an approach which was automated. A recent change meant the id values used were no longer simple alphabetic characters and included numbers and special characters.

I ended up using CSS.escape: https://developer.mozilla.org/en-US/docs/Web/API/CSS/escape

console.log(CSS.escape('1'));

First, this is the failing case:

const theId = "1";
document.querySelector(`#${theId}`);
const el = document.querySelector(`#${theId}`);
el.innerHTML = "After";
<div id="1">Before</div>

And now using CSS.escape:

const theId = "1";
const el = document.querySelector(`#${CSS.escape(theId)}`);
el.innerHTML = "After";
<div id="1">Before</div>

See how it correctly changes to show After, demonstrating the selector worked!

Upvotes: 56

Dennis
Dennis

Reputation: 32598

It is valid, but requires some special handling. From here: http://mathiasbynens.be/notes/css-escapes

Leading digits

If the first character of an identifier is numeric, you’ll need to escape it based on its Unicode code point. For example, the code point for the character 1 is U+0031, so you would escape it as \000031 or \31 .

Basically, to escape any numeric character, just prefix it with \3 and append a space character ( ). Yay Unicode!

So your code would end up as (CSS first, JS second):

#\31  {
    background: hotpink;
}

document.getElementById('1');
document.querySelector('#\\31 ');

Upvotes: 155

Niet the Dark Absol
Niet the Dark Absol

Reputation: 324620

Because while they are valid in the HTML5 spec, they are not valid in CSS, which is what "query selector" means.

Instead, you would have to do this: document.querySelector("[id='1']"), which is very long-winded considering you could give it a meaningful ID like message1 or something ;)

Upvotes: 142

Related Questions