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Using modern JavaScript features in scripts

The default JavaScript engine is GraalVM, which is based on ECMAScript 2022 (more formally, ECMA-262, 13th edition). This means you can use modern JavaScript features from ECMAScript 2022 in your scripts.


GraalVM enables you to use modern JavaScript features such as:

  • let and const for variable declarations
  • Arrow functions
  • Template literals
  • Destructuring
  • Classes

To use the GraalVM JavaScript engine, you need to be running Imposter v4.0.0 or later.


For examples, see the examples/graal directory in GitHub.

Simple example

Start the mock server:

imposter up examples/graal/simple

Send a request to the mock server:

curl -i http://localhost:8080?name=Ada

Hello Ada

Advanced example

See the examples/graal/es6 directory for an example of using modern JavaScript features in a script.

Further reading