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Execute JavaScript code in the browser context. This is useful for advanced interactions, reading page state, or performing actions that require direct DOM manipulation.

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Usage

from smooth import SmoothClient

client = SmoothClient()

with client.session() as session:
    session.goto("https://example.com")

    # Get the page title
    result = session.evaluate_js("document.title")
    print(f"Page title: {result.output}")

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Request

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code
string
required
The JavaScript code to execute in the browser. The code should be an expression or a function that returns a value.Example: document.title
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args
dict
Optional dictionary of arguments to pass to the JavaScript function. When using args, your code must be a function that receives args as its parameter.Example: {"selector": ".product-price", "index": 0}

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Response

Returns an object with the following attributes.
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output
any
The result of the JavaScript evaluation. Complex objects are serialized to JSON.
​
credits_used
float
The number of credits used for this action. 1 credit corresponds to $0.01.
​
duration
float
The duration in seconds taken to execute the JavaScript.

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Examples

Read page information: 
with client.session() as session:
    session.goto("https://example.com")

    # Get current URL
    result = session.evaluate_js("window.location.href")
    print(f"Current URL: {result.output}")

    # Get page title
    result = session.evaluate_js("document.title")
    print(f"Title: {result.output}")

    # Check if an element exists
    result = session.evaluate_js("!!document.querySelector('.login-button')")
    print(f"Has login button: {result.output}")
Extract data from the DOM: 
with client.session() as session:
    session.goto("https://example.com/products")

    result = session.evaluate_js("""
        Array.from(document.querySelectorAll('.product-card')).map(card => ({
            name: card.querySelector('.name').textContent,
            price: parseFloat(card.querySelector('.price').textContent.replace('$', ''))
        }))
    """)

    for product in result.output:
        print(f"{product['name']}: ${product['price']}")
With arguments: 
with client.session() as session:
    session.goto("https://example.com")

    result = session.evaluate_js(
        "(args) => { return document.querySelectorAll(args.selector).length; }",
        args={"selector": ".product-item"}
    )
    print(f"Found {result.output} products")
Scroll the page: 
with client.session() as session:
    session.goto("https://example.com/infinite-scroll")

    # Scroll to bottom to load more content
    session.evaluate_js("window.scrollTo(0, document.body.scrollHeight)")

    # Wait a moment for content to load, then extract
    session.run_task("Wait for new content to load")
    data = session.extract({"type": "array", "items": {"type": "object", "properties": {"title": {"type": "string"}}}})
Interact with page elements: 
with client.session() as session:
    session.goto("https://example.com/form")

    # Set a value directly
    session.evaluate_js(
        "(args) => { document.querySelector(args.selector).value = args.value; }",
        args={"selector": "#email", "value": "[email protected]"}
    )

    # Click a button
    session.evaluate_js("document.querySelector('#submit-btn').click()")
Check page state before proceeding: 
with client.session() as session:
    session.goto("https://example.com")
    session.run_task("Log in with my credentials")

    # Verify login succeeded
    result = session.evaluate_js("""
        {
            isLoggedIn: !!document.querySelector('.user-avatar'),
            username: document.querySelector('.username')?.textContent || null
        }
    """)

    if result.output['isLoggedIn']:
        print(f"Logged in as {result.output['username']}")
        session.run_task("Go to my account settings")
    else:
        print("Login failed")