Element.hasAttribute()

The Element.hasAttribute() method returns a Boolean value indicating whether the specified element has the specified attribute or not.

Syntax

hasAttribute(name)

A boolean.

const foo = document.getElementById("foo");
if (foo.hasAttribute("bar")) {
    // do something
}

DOM methods dealing with element's attributes:

Not namespace-aware, most commonly used methods	Namespace-aware variants (DOM Level 2)	DOM Level 1 methods for dealing with `Attr` nodes directly (seldom used)	DOM Level 2 namespace-aware methods for dealing with `Attr` nodes directly (seldom used)
`setAttribute` (DOM 1)	`setAttributeNS`	`setAttributeNode`	`setAttributeNodeNS`
`getAttribute` (DOM 1)	`getAttributeNS`	`getAttributeNode`	`getAttributeNodeNS`
`hasAttribute` (DOM 2)	`hasAttributeNS`	-	-
`removeAttribute` (DOM 1)	`removeAttributeNS`	`removeAttributeNode`	-

Specification
DOM Standard # ref-for-dom-element-hasattribute①

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