What are valid values for the id attribute in HTML-第3页回答

2楼-- · 2020-01-22 11:10

Since ES2015 we can as well use -almost- all unicode characters for ID's, if the document charset is set to UTF8.

Test out here: https://mothereff.in/js-variables

Read about: https://mathiasbynens.be/notes/javascript-identifiers-es6

In ES2015, identifiers must start with $, _, or any symbol with the Unicode derived core property ID_Start.

The rest of the identifier can contain $, _, U+200C zero width non-joiner, U+200D zero width joiner, or any symbol with the Unicode derived core property ID_Continue.

const target = document.querySelector("div").id
console.log(
   target
)
document.getElementById(target).style.backgroundColor = "black"

div {
  border: 1px black solid;
  width: 100%;
  height: 200px
}

<div id="H̹̙̦̮͉̩̗̗ͧ̇̏̊̾Eͨ͆͒̆ͮ̃͏̷̮̣̫̤̣Cͯ̂͐͏̨̛͔̦̟͈̻O̜͎͍͙͚̬̝̣̽ͮ͐͗̀ͤ̍̀͢M̴̡̲̭͍͇̼̟̯̦̉̒͠Ḛ̛̙̞̪̗ͥͤͩ̾͑̔͐ͅṮ̴̷̷̗̼͍̿̿̓̽͐H̙̙̔̄͜">

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ら.Afraid

3楼-- · 2020-01-22 11:14

for HTML5

The value must be unique amongst all the IDs in the element’s home subtree and must contain at least one character. The value must not contain any space characters.

At least one character, no spaces.

This opens the door for valid use cases such as using accented characters. It also gives us plenty of more ammo to shoot ourselves in the foot with, since you can now use id values that will cause problems with both CSS and JavaScript unless you’re really careful.

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啃猪蹄的小仙女

4楼-- · 2020-01-22 11:15

From the HTML 4 spec...

ID and NAME tokens must begin with a letter ([A-Za-z]) and may be followed by any number of letters, digits ([0-9]), hyphens ("-"), underscores ("_"), colons (":"), and periods (".").

EDIT: d'oh! Beaten to the button, again!

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做个烂人

5楼-- · 2020-01-22 11:17

In practice many sites use id attributes starting with numbers, even though this is technically not valid HTML.

The HTML 5 draft specification loosens up the rules for the id and name attributes: they are now just opaque strings which cannot contain spaces.

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甜甜的少女心

6楼-- · 2020-01-22 11:18

IDs are best suited for naming parts of your layout so should not give same name for ID and class
ID allows alphanumeric and special characters
but avoid using of # : . * ! symbols
not allowed spaces
not started with numbers or a hyphen followed by a digit
case sensitive
using ID selectors is faster than using class selectors
use hyphen "-" (underscore "_" can also use but not good for seo) for long CSS class or Id rule names
If a rule has an ID selector as its key selector, don’t add the tag name to the rule. Since IDs are unique, adding a tag name would slow down the matching process needlessly.
In HTML5, the id attribute can be used on any HTML element and In HTML 4.01, the id attribute cannot be used with: <base>, <head>, <html>, <meta>, <param>, <script>, <style>, and <title>.

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贪生不怕死

7楼-- · 2020-01-22 11:21

You can technically use colons and periods in id/name attributes, but I would strongly suggest avoiding both.

In CSS (and several JavaScript libraries like jQuery), both the period and the colon have special meaning and you will run into problems if you're not careful. Periods are class selectors and colons are pseudo-selectors (eg., ":hover" for an element when the mouse is over it).

If you give an element the id "my.cool:thing", your CSS selector will look like this:

#my.cool:thing { ... /* some rules */ ... }

Which is really saying, "the element with an id of 'my', a class of 'cool' and the 'thing' pseudo-selector" in CSS-speak.

Stick to A-Z of any case, numbers, underscores and hyphens. And as said above, make sure your ids are unique.

That should be your first concern.

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What are valid values for the id attribute in HTML

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