Function getModeForUsageLocation

Use program.getModeForUsageLocation, which retrieves the correct compilerOptions, instead of this function whenever possible. Calculates the final resolution mode for a given module reference node. This function only returns a result when module resolution settings allow differing resolution between ESM imports and CJS requires, or when a mode is explicitly provided via import attributes, which cause an import or require condition to be used during resolution regardless of module resolution settings. In absence of overriding attributes, and in modes that support differing resolution, the result indicates the syntax the usage would emit to JavaScript. Some examples:

// tsc foo.mts --module nodenext
import {} from "mod";
// Result: ESNext - the import emits as ESM due to `impliedNodeFormat` set by .mts file extension

// tsc foo.cts --module nodenext
import {} from "mod";
// Result: CommonJS - the import emits as CJS due to `impliedNodeFormat` set by .cts file extension

// tsc foo.ts --module preserve --moduleResolution bundler
import {} from "mod";
// Result: ESNext - the import emits as ESM due to `--module preserve` and `--moduleResolution bundler`
// supports conditional imports/exports

// tsc foo.ts --module preserve --moduleResolution node10
import {} from "mod";
// Result: undefined - the import emits as ESM due to `--module preserve`, but `--moduleResolution node10`
// does not support conditional imports/exports

// tsc foo.ts --module commonjs --moduleResolution node10
import type {} from "mod" with { "resolution-mode": "import" };
// Result: ESNext - conditional imports/exports always supported with "resolution-mode" attribute
Copy