Target

The target setting determines which JavaScript features are downleveled (transformed to older syntax) and which are left intact in the output. This allows you to control the compatibility of your bundled code with specific environments or JavaScript versions.

For example, an arrow function () => this will be transformed into an equivalent function expression if the target is es5 or lower.

Syntax Downgrade Only

The target option only affects syntax transformations. It does not include runtime polyfills or shims for APIs that may not exist in the target environment. For example, if your code uses Promise, it will not be polyfilled for environments that lack native Promise support.

Customizing the Target

You can specify the target using the --target option:

tsdown --target <target>

Supported Targets

tsdown supports a wide range of targets, including:

• ECMAScript versions: es5, es2015, es2020, esnext, etc.
• Browser versions: chrome100, safari18, firefox110, etc.
• Node.js versions: node20.18, node16, etc.

Example

tsdown --target es2020

You can also pass an array of targets to ensure compatibility across multiple environments. For example:

tsdown --target chrome100 --target node20.18