CODEWITHSUNDEEP
javascripthtml
CodeYogi
CodeYogi

Reputation: 1412

How to check if an attribute is a Boolean attribute?

Is there any way to check if some HTML attribute are Boolean? for example:

<input type="text" name="input" disabled=""/>

Here the disabled attribute is Boolean, I have some code and I need check before setting value whether that attribute is Boolean or not.

Why I need this?

As mentioned here we can have either "" or property name itself as the valid value not true or false.

Upvotes: 3

Views: 2955

Answers (2)

deceze
deceze

Reputation: 522081

There's basically no distinction on the level of HTML. If the attribute is simply the name without value, e.g. <input disabled>, that's a sure sign that it's a boolean attribute. However, if it's using the name="value" notation, then there's no way to distinguish it. Is class="class" a boolean attribute? No, it's a classList with one entry "class". How about foo=""? Well, it's either a boolean attribute opting for the empty-value notation, or it's an attribute with no value set.

Only the interpreter assigns boolean-ness to an attribute; i.e. while parsing the HTML into a DOM, the interpreter sets DOM attributes like this, roughly speaking:

domElement.disabled = htmlElement.hasAttribute('disabled');

If you want to know what HTML elements are booleans, you need to do the same thing an interpreter does: keep a list of DOM elements whose attributes have types and interpret the HTML according to that specification.

Upvotes: 3

d_z90
d_z90

Reputation: 1263

To solve this issue, you have the typeof operand in the following way:

var check_input = document.getElementById("check-input");

if(typeof(check_input.disabled) === "boolean"){
  alert('Yes');
}

Here is a JSfiddle with the complete code. I hope that my answer can help you!

Upvotes: 0

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