How to check that element has either of classes in Cypress?

Cypress .should() wraps chai assertions, so from how to do an “or” in chai should

the following html fragment

<div id="1" class="class1"></div>
<div id="2" class="class2"></div>
<div id="3" class="class1 class2"></div>
<div id="4" class="class3"></div>

can be tested like this

it('finds either class1 or class2', () => {

  cy.get('div#1')
    .should('satisfy', ($el) => {
      const classList = Array.from($el[0].classList); 
      return classList.includes('class1') || classList.includes('class2') // passes
    }) 

  cy.get('div#2')
    .should('satisfy', ($el) => {
      const classList = Array.from($el[0].classList); 
      return classList.includes('class1') || classList.includes('class2') // passes
    }) // passes

  cy.get('div#3')
    .should('satisfy', ($el) => {
      const classList = Array.from($el[0].classList); 
      return classList.includes('class1') || classList.includes('class2') // passes
    }) 

  cy.get('div#4')
    .should('satisfy', ($el) => {
      const classList = Array.from($el[0].classList); 
      return classList.includes('class1') || classList.includes('class2') // fails
    }) 

})

Notes

• the param to the function is a jquery object, so use $el[0] to reference the element
• $el[0].classList return a DomTokenList which is array-like, so use Array.from() to apply the Array method .includes() to it.

You can also make things a bit more generic by extracting the function,

it('finds either class1 or class2', () => {

  const hasAtLeastOneClass = (expectedClasses) => {
    return ($el) => {
      const classList = Array.from($el[0].classList); 
      return expectedClasses.some(expectedClass => classList.includes(expectedClass));
    }
  }

  cy.get('div#1').should('satisfy', hasAtLeastOneClass(['class1', 'class2']));  //passes

  cy.get('div#2').should('satisfy', hasAtLeastOneClass(['class1', 'class2']));  //passes

  cy.get('div#3').should('satisfy', hasAtLeastOneClass(['class1', 'class2']));  //passes

  cy.get('div#4').should('satisfy', hasAtLeastOneClass(['class1', 'class2']));  //fails

})