How to use the Run Script block

The Run script block allows you to execute JavaScript code within your project. Below are its functionalities, limitations, and examples to guide proper usage.

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Key Features

• The Script block enables you to execute JavaScript code, but it does not allow you to create custom visual blocks.
• Variables in the script are evaluated, not parsed, so they must be treated as real JavaScript variables.

Note: Use console.log({{My variable}}) instead of console.log("{{My variable}}").

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setVariable Function

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Purpose

If you want to set a variable value with Javascript, the Set Variable is more appropriate for most cases. However setVariable function allows you to set values within a Script block.

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Example

if ({{My variable}} === 'foo') {
  setVariable('My variable', 'bar');
} else {
  setVariable('My variable', 'other');
}

Important:

• The setVariable function is only available in scripts executed on the server.
• It will not work if the Execute on client? option is checked.

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Server-Side Script Limitations

When scripts are executed on the server, they run in a secure, isolated environment. As a result, some JavaScript functionalities are restricted:

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Restricted Functions

• Global functions like console.log, setTimeout, and setInterval are not available.
• Importing external libraries using import or require is not supported.
• Browser APIs like window, document, and localStorage are not accessible.

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Fetch Behavior

The behavior of the fetch function differs from the native implementation:

• The response will always be a string, even if the server returns a JSON object.
• You need to manually parse the response using JSON.parse().

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Examples:

// ❌ This throws an error
const response = await fetch('https://jsonplaceholder.mycode.com/todos/1');
const data = await response.text();

// ✅ Correct usage
const response = await fetch('https://jsonplaceholder.mycode.com/todos/1');
const data = JSON.parse(response);

Note: Avoid using await response.text() or await response.json().

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Client-Side Script Execution

If you need access to browser APIs, ensure the Execute on client? option is checked. This allows the script to run in the user’s browser.

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Examples:

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Reload Page

window.location.reload();

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Redirect Based on Variable Value

if ({{Category}} === 'qualified') {
  window.location.href = 'https://my-site.com';
}