Why cy.first(), cy.last(), cy.eq() in Cypress? - Purpose & Use Cases

The Big Idea

What if you could pick exactly the right item on a page every time, without scrolling or guessing?

The Scenario

Imagine you have a long list of items on a webpage, and you want to check just the first, last, or a specific item manually by clicking and inspecting each one.

This means scrolling, clicking, and guessing if you picked the right element every time.

The Problem

Manually finding elements is slow and tiring.

You might click the wrong item or miss changes in the list order.

It's easy to make mistakes and hard to repeat the exact steps consistently.

The Solution

Using cy.first(), cy.last(), and cy.eq() lets you directly pick the first, last, or any specific item in a list automatically.

This saves time, reduces errors, and makes your tests clear and reliable.

Before vs After

✗ Before

cy.get('li').then(items => {
  const first = items[0];
  // manual checks here
})

✓ After

cy.get('li').first().should('be.visible')

What It Enables

You can quickly and confidently test specific elements in a list without guessing or extra steps.

Real Life Example

Testing a shopping cart where you want to check the first product's price, the last product's name, or the third product's quantity easily.

Key Takeaways

Manual element selection is slow and error-prone.

cy.first(), cy.last(), and cy.eq() pick elements directly and reliably.

This makes tests faster, clearer, and less buggy.

Practice

1. What does cy.first() do in Cypress testing?

easy

A. Selects all elements matching a selector

B. Selects the last element from a group of matched elements

C. Selects the first element from a group of matched elements

D. Selects an element by its CSS class

Solution

1. Step 1: Understand the purpose of cy.first()

   cy.first() is used to pick the very first element from a list of elements found by a selector.

2. Step 2: Compare with other options

   Options A, B, and C describe different behaviors: last element, selecting by class, or selecting all elements, which are not what cy.first() does.

3. Final Answer:

   Selects the first element from a group of matched elements -> Option C

4. Quick Check:

   cy.first() = first element [OK]

Hint: Remember: first() picks the very first element [OK]

Common Mistakes:

• Confusing first() with last()
• Thinking first() selects by class or id
• Assuming first() selects all elements

2. Which of the following is the correct syntax to select the third element in a list using Cypress?

easy

A. cy.get('li').eq(2)

B. cy.get('li').eq(3)

C. cy.get('li').first(3)

D. cy.get('li').last(3)

Solution

1. Step 1: Recall zero-based indexing in eq()

   The eq() command uses zero-based index, so the third element is at index 2.

2. Step 2: Check syntax correctness

   cy.get('li').eq(2) uses eq(2) correctly. Options A, C, and D either use wrong index or invalid syntax.

3. Final Answer:

   cy.get('li').eq(2) -> Option A

4. Quick Check:

   Third element index = 2 [OK]

Hint: Remember eq() uses zero-based index, so third is eq(2) [OK]

Common Mistakes:

• Using eq(3) for the third element
• Trying to pass a number to first() or last()
• Confusing eq() with first() or last()

3. Given the following HTML:

<ul>
  <li>Apple</li>
  <li>Banana</li>
  <li>Cherry</li>
  <li>Date</li>
</ul>

What text will cy.get('li').last().invoke('text') return?

medium

A. "Cherry"

B. "Apple"

C. "Banana"

D. "Date"

Solution

1. Step 1: Identify what cy.last() selects

   cy.last() picks the last element in the matched list, which is the <li> containing "Date".

2. Step 2: Understand invoke('text')

   This command extracts the text content of the selected element, so it returns "Date".

3. Final Answer:

   "Date" -> Option D

4. Quick Check:

   last() element text = "Date" [OK]

Hint: last() picks last element's text content [OK]

Common Mistakes:

• Selecting first element text instead of last
• Confusing zero-based index with last()
• Expecting eq(3) to return "Date" without zero-based indexing

4. Consider this Cypress code snippet:

cy.get('button').eq(5).click()

It throws an error: "Cannot read property 'click' of undefined". What is the most likely cause?

medium

A. There are fewer than 6 buttons on the page, so eq(5) returns undefined

B. The syntax of eq() is incorrect; it should be eq[5]

C. click() cannot be chained after eq()

D. The selector 'button' is invalid

Solution

1. Step 1: Understand eq() index and element count

   eq(5) tries to select the 6th element (index 5). If fewer than 6 buttons exist, it returns undefined.

2. Step 2: Analyze error message

   The error "Cannot read property 'click' of undefined" means the element does not exist, so click() fails.

3. Final Answer:

   There are fewer than 6 buttons on the page, so eq(5) returns undefined -> Option A

4. Quick Check:

   Index out of range = undefined element [OK]

Hint: Check element count before using eq(index) [OK]

Common Mistakes:

• Using wrong eq() syntax
• Assuming click() can't chain after eq()
• Ignoring zero-based index causing out-of-range

5. You want to click the second-to-last item in a list of elements matched by cy.get('.item'). Which Cypress command chain correctly achieves this?

hard

A. cy.get('.item').eq(cy.get('.item').its('length').then(len => len - 2)).click()

B. cy.get('.item').eq(-2).click()

C. cy.get('.item').eq(-1).click({ force: true })

D. cy.get('.item').eq(cy.get('.item').length - 2).click()

Solution

1. Step 1: Recall eq() indexing in Cypress

   Cypress eq(n) supports negative indices: eq(-1) is last, eq(-2) is second-to-last.

2. Step 2: Compare options

   Options A and B have invalid syntax passing chainables to eq(). cy.get('.item').eq(-1).click({ force: true }) uses eq(-1) for last item. cy.get('.item').eq(-2).click() correctly uses eq(-2).

3. Final Answer:

   cy.get('.item').eq(-2).click() -> Option B

4. Quick Check:

   eq(-2) = second-to-last [OK]

Hint: eq() supports negative indices: -2 for second-to-last [OK]

Common Mistakes:

• Using negative index in eq() incorrectly (e.g., -1 instead of -2)
• Trying to subtract length directly without .then()
• Passing Cypress chainable as eq() argument