SyntaxError: Unexpected token ‘||=’ on import of pdfjs-dist – Error Solution Guide

Error Overview

The error message “SyntaxError: Unexpected token '||=' on import of pdfjs-dist” indicates that there is a syntax issue within the JavaScript code associated with the import of the pdfjs-dist library. This specific error typically occurs when the JavaScript engine encounters a token that it does not recognize or expects in a different context, leading to a failure in parsing the code. The use of the token ||= signifies a logical OR assignment, which is not supported in older JavaScript environments.

This error can arise in various scenarios, especially when using modern JavaScript features in contexts that do not fully support them. Understanding the root causes and potential solutions is essential for developers working with the pdfjs-dist library.

Common Causes

Several common causes may lead to the “SyntaxError: Unexpected token '||=' on import of pdfjs-dist” error:

1. Outdated JavaScript Environment: The JavaScript engine in use may not support the latest syntax introduced in ES2021, such as the logical assignment operators.
2. Incorrect Module Bundler Configuration: If you are using a module bundler like Webpack or Rollup, the configuration may not be set to transpile modern JavaScript syntax properly.
3. Incompatible Version of pdfjs-dist: Using an older version of pdfjs-dist that does not support the current syntax may lead to this error.
4. Browser Compatibility: Some older browsers may not support modern JavaScript features, causing this error when running the code.
5. Improper Import Statement: The way the pdfjs-dist library is being imported may not be compatible with the environment.

Solution Methods

To resolve the “SyntaxError: Unexpected token '||=' on import of pdfjs-dist” error, consider the following methods:

Method 1: Update Your JavaScript Environment

1. Check your Node.js version by running the following command in your terminal:
   bash
node -v
2. If the version is below 14.x, consider updating Node.js to a more recent version that supports ES2021 features.
3. After upgrading, verify that your environment recognizes the new syntax by testing a simple script that uses ||=.

Method 2: Configure Your Module Bundler

1. If you are using Webpack, ensure that you have the necessary loaders installed to transpile modern JavaScript:
   bash
npm install --save-dev babel-loader @babel/core @babel/preset-env
2. Create or update your Babel configuration file (babel.config.js) with the following content:
   “`javascript
   module.exports =