Element Selectors

Element Selectors are similar to CSS Keywords in both purpose and syntax.

Most test actions (e.g., the click action) require a target (e.g., a button). Assertions — conditions that you set to see if a test succeeded — also need to examine the page.

To locate action and assertion targets, as well as extract other information from the DOM, you need to create Element Selector queries.

Selectors filter the DOM and return page elements that match your criteria. Element Selectors look like this:

Selector('#big-red-button');

Every TestCafe test contains Element Selectors. It is important to have a good understanding of Selectors to write TestCafe tests efficiently.

Table of Contents

Introduction

Actions and assertions use Selector query arguments to locate their targets:

t.click('#big-red-button');

The t.click action targets the result of the #big-red-button Selector query. This query matches elements with the big-red-button ID.

Additionally, you can execute standalone Selector queries to examine the page:

const headerText = await Selector('#header').textContent;

The query above returns the textContent of the #header element.

Element Selector Basics

Selector queries begin with an invocation of the Selector() constructor. Constructor arguments determine the initial results of the Selector query.

Selector(/*arguments go here*/);

There are three ways to initialize a Selector. The most common way is to use a CSS Keyword:

Selector('button');

The Selector above returns all the button elements on the page.

After you initialize a Selector, you can perform additional actions with the results of the query. Append Selector methods to the constructor:

Selector('button').withText('click me');

The withText method helped you narrow down the results. The query above only matches button elements with the “click me” label.

Use Element Selectors with Actions and Assertions

Actions and assertions use Selector queries to identify their targets.

Note

TestCafe actions can’t target pseudo-elements and require additional code to target the Shadow DOM.

You can pass any valid Selector query to an action or an assertion:

t.click(Selector('#big-red-button'));

If your Selector query does not include methods, you can omit the Selector keyword:

t.click('#big-red-button');

Simple Selectors and Compound Selectors

Simple Selectors filter the DOM once:

Selector('#big-red-button');

Compound Selectors filter the DOM multiple times:

Selector('nav .button');
// or 
Selector('nav').find('.button')

The example above matches button class elements that reside inside nav blocks.

How Selectors Work

Selectors are asynchronous.

TestCafe executes Selector queries when it encounters them in actions and assertions.

Element selectors can return multiple items. The selector.count property indicates the number of page elements that match the query.

If a page action / assertion Selector matches multiple DOM elements, TestCafe performs the action / assertion with the first matching element.

If a Selector query yields zero matches, its return value is null. If a test action uses this Selector, the test fails. If you pass such a Selector to an assertion that expects a non-null return value, the test fails, too:

await t.expect(Selector('.holyGrail').count).eql(1)
.expect(Selector('.holyGrail').exists).ok()

If you save a Selector query to a variable, TestCafe only executes the query when you call or await that variable.

The example below contains three identical actions. Yet, since every action changes the DOM, each call of the buttons variable yields a different result.

test('Click a button', async t => {
    const buttons = Selector('button').withText("A button number");

    await t
        .click(buttons.nth(0))
        .click(buttons.nth(0))
        .click(buttons.nth(0))
});
<html>
    <body>
        <div>
        <button onclick= "this.textContent= 'Pressed';">A button number 1</button>
        <button onclick= "this.textContent= 'Pressed';">A button number 2</button>
        <button onclick= "this.textContent= 'Pressed';">A button number 3</button>
        </div>
    </body>
</html>

Selector Types

Additional libraries enable the use of Framework-Specific Selectors.

Keyword-Based Selectors

Keyword-Based Selectors filter the page in search of elements that match CSS keywords.

Selector('#some-element');

A few examples:

  • body matches the body element.
  • .login matches elements with the login class name.
  • #input matches the first element with the input ID.

Selector Keywords

TestCafe Selector keywords are syntactically identical to CSS Selectors.

Top Tip: Use Custom HTML Attributes

Keywords that reference custom HTML attributes are more reliable, because they don’t reference mutable code.

  • Selectors break when you change the page code that they reference.
  • Bad Selectors reference class names or DOM relationships – things that change fairly often during development.
  • Reliable Selectors reference properties that are independent of page design and layout.

Mark your actions’ targets with custom HTML attributes, and write better, more reliable Selectors.

  1. Add a custom HTML attribute (for example: data-test-id) to all the page elements that your test interacts with.
  2. Reference your attribute when you write Selector queries:
t.click('button').withAttribute('data-test-id','left-button') // or
t.click('[data-test-id="left-button"]')

Function-based Selectors

Function-based Selectors execute a client-side function that traverses the DOM and returns one of the following objects:

  • A DOM node
  • An array of DOM nodes
  • A NodeList object
  • An HTMLCollection object
  • A null object
  • An undefined object

The function-based Selector below retrieves a string from localStorage and finds a DOM element with the identical ID:

const element = Selector(() => {
    const storedElementId = window.localStorage.storedElementId;
    return document.getElementById(storedElementId);
});

Function-based Selectors can have additional parameters:

const elementWithId = Selector(id => {
    return document.getElementById(id);
});

await t.click(elementWithId('buy'));

Selector-Based Selectors

You can create Selectors based on other Selectors. This is an easy way to extend existing Selector queries or filter their results.

Copy and extend another Selector’s query

You can create a new Selector based on another Selector’s query.

The example code below saves a simple Selector query to the parent variable. It then declares a child variable that adds the find method to the original Selector.

const parent = Selector('div'); // filters the DOM
const child = parent.find('button'); // inherits the "parent" query, modifies it, and filters the DOM again

Note that the child Selector does not inherit the return value of the parent Selector.

You can also nest Selectors. If you pass Selector A to Selector B as an argument, Selector B inherits Selector A’s query. This is an easy way to create a Selector copy with modified options.

The example below saves a simple Selector query to the ctaButton variable and passes it to another Selector. As a result, the second Selector inherits the first Selector’s query. However, since the second Selector enables the visibilityCheck option, it only matches visible elements.

const ctaButton = Selector('.cta-button'); // 
Selector(ctaButton, { visibilityCheck: true });

You can even pass arguments to Selectors within Selectors:

const elementWithIdOrClassName = Selector(value => {
    return document.getElementById(value) || document.getElementsByClassName(value);
});
const submitButton = Selector(elementWithIdOrClassName('main-element'));

Copy and filter another Selector’s results

You can create a new Selector based on another Selector’s return value.

If you want to copy the query’s return value, you need to asynchronously execute the query. Asynchronous Selector calls return a DOM Node State object that contains the query’s results. If you pass this object to another Selector, you can filter the original Selector’s results.

In the example below, the visibleTopMenu Selector filters the return value of the topMenuSnapshot Selector. Since it contains an additional visibilityCheck option, it only returns visible elements.

const topMenuSnapshot = await Selector('#top-menu')(); // TestCafe executes this query asynchronously, filters the DOM and returns a DOMNodeState object.
const visibleTopMenu = Selector(topMenuSnapshot, { visibilityCheck: true }); // TestCafe doesn't filter the DOM. It only filters the results of the topMenuSnapshot query

Selector Options

You can customize the behavior of Selectors with constructor options.

Override Selector Options

Use the with method to override the options of another Selector.

import { Selector } from 'testcafe';

const elementWithId = Selector(id => document.getElementById(id));

fixture `My fixture`
    .page `http://www.example.com/`;

test('My Test', async t => {
    const visibleElementWithId = elementWithId.with({
        visibilityCheck: true
    });

    const visibleButton = await visibleElementWithId('submit-button');
});

Selector Methods

Selector methods perform additional actions with the return value of the main Selector query. Selector methods narrow, expand, or otherwise modify the selection of page elements.

Selector('keyword1 keyword2').method1().method2();

Why use Selector Methods

Keyword-based Selectors have limited capabilities.

Complex keyword-based Selectors are long and difficult to maintain:

await t.click('div > .my-class > div:nth-child(2) > span > a[href="https://my-site.com/page"]');

CSS selectors cannot query parent elements:

<html>
    <body>
        <!-- ... -->
                    <div>
                        <!-- you cannot query this div by its child's ID -->
                        <div>
                            <div id="query-my-parent"></div>
                        </div>
                    </div>
        <!-- ... -->
    </body>
</html>

Selector methods can overcome these limitations and freely traverse the DOM tree:

const link = Selector('div')
    .child('.my-class')
    .child('div')
    .nth(2)
    .child('span')
    .child('a')
    .withAttribute('href', 'https://my-site.com/page');

const parent = Selector('#query-my-parent').parent();

Selector Method Types

Filter Methods

Filter methods filter the page element selection.

Method Description
nth Finds the element with the specified index. The index starts at 0. Negative index values indicate the element’s location relative to the final element of the array.
withText Finds elements with a textContent value that contains the specified case-sensitive string or matches the regular expression.
withExactText Finds elements with a textContent value equal to the specified string (case-sensitive).
withAttribute Finds elements with the specified attribute or attribute value.
filterVisible Finds visible elements.
filterHidden Finds hidden elements.
filter Finds elements that match a CSS selector, or meet the conditions of a filter function.

Related element lookup methods find elements related to the existing element selection.

Method Description
find Returns an array of descendant nodes that match a CSS Selector, or meet the conditions of a filter function.
parent Returns an array of parent elements.
child Returns an array of child elements.
sibling Returns an array of sibling elements.
nextSibling Returns an array of succeeding sibling elements.
prevSibling Returns an array of preceding sibling elements.
shadowRoot Returns the shadow root node.

Framework-Specific Selectors

Users of popular front-end frameworks can simplify their Selectors with the help of special TestCafe plugins.

For instance, users that install the testcafe-react-selectors plugin can reference the React component tree.

Note

Front-end development tools (such as React DevTools or Vue DevTools) can interfere with TestCafe and cause errors. Do not open them when you run or debug TestCafe tests.

React

Install the testcafe-react-selectors npm package.

Import the ReactSelector method to reference React components by name.

For more information, refer to the official plugin documentation.

import { ReactSelector } from 'testcafe-react-selectors';
const reactComponent      = ReactSelector('MyComponent');
const reactComponentState = await reactComponent.getReact();

// >> reactComponentState
//
// {
//     props:    <component_props>,
//     state:    <component_state>
// }

Angular

Install the testcafe-angular-selectors npm package.

Import the AngularSelector method to reference Angular components by name. Call the method without parameters to obtain the project’s root element.

For more information, refer to the official plugin documentation.

import { AngularSelector } from 'testcafe-angular-selectors';

const rootAngular       = AngularSelector();
const list        = AngularSelector('list');
const listAngular = await list.getAngular();

await t.expect(listAngular.testProp).eql(1);

AngularJS

Install the testcafe-angular-selectors npm package. Import the AngularJSSelector method to look for DOM elements by their Angular binding.

For more information, refer to the official plugin documentation.

import { AngularJSSelector } from 'testcafe-angular-selectors';
import { Selector } from 'testcafe';

fixture `TestFixture`
    .page('http://todomvc.com/examples/angularjs/');

test('add new item', async t => {
    await t
        .typeText(AngularJSSelector.byModel('newTodo'), 'new item')
        .pressKey('enter')
        .expect(Selector('#todo-list').visible).ok();
});

Vue

Install the testcafe-vue-selectors npm package.

Import the VueSelector method to reference Vue components by name.

For more information, refer to the official plugin documentation.

import VueSelector from 'testcafe-vue-selectors';

const rootVue   = VueSelector();
const vueComponent      = VueSelector('componentTag');
const vueComponentState = await vueComponent.getVue();

// >> vueComponentState
//
// {
//     props:    <component_props>,
//     state:    <component_state>,
//     computed: <component_computed>
// }

Aurelia

Install the testcafe-aurelia-selectors plugin.

Import the AureliaSelector method to look for elements by their Aurelia binding.

For more information, refer to the official plugin documentation.

import AureliaSelector from 'testcafe-aurelia-selectors';

fixture `TestFixture`
    .page('http://todomvc.com/examples/aurelia/');

test('add new item', async t => {
    await t
        .typeText(AureliaSelector.byValueBind('newTodoTitle'), 'new item')
        .pressKey('enter')
        .expect(AureliaSelector.byShowBind('items.length').exists).ok();
});

Reuse Element Selectors

Tests that repeat identical Selector queries are slower and harder to maintain. You can reuse Selectors in one of the two ways:

Assign the value of a Selector query to a constant, and use that constant later in code. Every time you invoke this constant, you execute the Selector query anew.

const myBeautifulSelector = Selector('div').withText('hello world'); // does not execute the query
<…>
await t.click(myBeautifulSelector); // executes the query

Selector queries take time to resolve. Await the Selector to execute the query once and only re-use its return value.

const myBeautifulSelector = await Selector('div').withText('hello world'); // executes the query
<…>
await t.click(myBeautifulSelector); // uses the query result from before

Selector Limitations

  • Selector queries cannot access user variables outside of their scope. If a Selector query needs to access a variable, pass that variable through the dependency option.
  • Keyword-based Selectors and Selector-based Selectors do not accept custom arguments. Use the dependencies option to pass additional data to a Selector query.
  • Function-based Selectors can not contain generators or async/await keywords.
  • Selector dependencies do not support property shorthands.

Element Selector Timeout

When TestCafe runs tests, it automatically waits for action targets to appear and become visible. The value of the element selector timeout variable defines the maximum waiting time. If a visible DOM element that matches a Selector query does not appear on the page within the element selector timeout, the test fails.

Use the timeout Selector option to specify a custom selector timeout.

Selector timeouts have no effect on Selector.exists and Selector.count properties. TestCafe calculates their values immediately. If you want to evaluate these properties in an assertion, set a custom assertion timeout.

await t.expect(Selector('#elementId', { timeout: 500 }).innerText).eql('text', 'check element text');

See Automatic Waiting for more information.

Access the Shadow DOM

You cannot access Shadow DOM elements directly. To interact with the Shadow DOM, identify the root node of a shadow tree, and use other Selector methods to traverse it.

Tip

Reuse shadowRoot Selector queries for greater convenience.

Warning

You cannot perform actions with the shadowRoot() element, or use it in assertions. Use this element as the shadow DOM entry point.

The following example returns the <p> element from the shadow DOM:

import { Selector } from 'testcafe';

fixture`Selector.shadowRoot`
    .page`https://devexpress.github.io/testcafe/example/`;

test('Get text within shadow tree', async t => {
    const shadowRoot = Selector('div').withAttribute('id', 'shadow-host').shadowRoot();
    const paragraph  = shadowRoot.child('p');

    await t.expect(paragraph.textContent).eql('This paragraph is in the shadow tree');

    try {
        await t.click(shadowRoot);
        // causes an error
        // do not target the shadow root directly or use it in assertions
    }
    catch (error) {
        await t.expect(error.code).eql('E27');
    }
});

Debug Selectors

If an action/assertion Selector does not match any DOM element, the test fails and TestCafe throws an error.

If a Selector method does not match any elements, TestCafe also throws an error. If you chain several Selector methods together, TestCafe stops the chain’s execution after the first unsuccessful Selector method.

Further Reading

The Advanced Selector Techniques guide describes the following advanced Selector techniques:

The Selector Recipes page features additional Selector code examples.