The comparison operator Expression


<expr> < <expr>
<expr> is less than <expr>
<expr> <= <expr>
<expr> is less than or equal to <expr>
<expr> > <expr>
<expr> is greater than <expr>
<expr> >= <expr>
<expr> is greater than or equal to <expr>
<expr> == <expr>
<expr> === <expr>
<expr> is <expr>
<expr> is equal to <expr>
<expr> is really equal to <expr>
<expr> is not <expr>
<expr> is not equal to <expr>
<expr> is not really equal to <expr>
<expr> equals <expr>
<expr> really equals <expr>
<expr> is empty
<expr> is not empty
I match <expr>
<expr> matches <expr>
I do not match <expr>
<expr> does not match <expr>
I contain <expr>
<expr> contains <expr>
<expr> is in <expr>
I do not contain <expr>
<expr> does not contain <expr>
<expr> includes <expr>
I do not include <expr>
<expr> does not include <expr>
<expr> is empty
<expr> is not empty
<expr> is a <type name>
<expr> is not a <type name>
<expr> exists
<expr> does not exist


Many comparison operators are similar to comparison operators in javascript. In addition to the usual comparison operators, hyperscript includes the english terms is and is not for == and != respectively.

The really modifier switches a comparison to use === or !==, depending on what it modifies.

Hyperscript also includes four additional operations, match, contain, include, exists and various syntaxes depending on what is being tested against. match will test if the left hand side matches the CSS query or Regular Expression string. contains will test if the left hand side contains OR includes the right hand side (invoking contains() or includes()). includes is identical to contains. exist test if the left hand side is not null and, if it is a collection of elements, it contains any elements.

The is in test effectively flips the left hand side and right hand side of the contains comparison.

You can also test if a value exists or not using the is empty and is not empty comparisons. Hyperscript considers "empty" values to be undefined, null, empty strings, and zero length arrays and objects. This works in the same way as the no expression.

Finally, you can test if a value is of a given type with the is a form

Note that all comparison operators have the same precedence, but if multiple distinct operators are used the expression must be parenthesized to avoid ambiguity.


  _="on click if <button/>.length > 1
                   log 'found multiple buttons!'"
  Find buttons

  _="on click if I match .active
                   log 'I'm active!'"
  Check if active