ts-morph-utils

Overview

A set of utilities to use with ts-morph. This package is still in its infancy, so there are some limitations, possible bugs with the utilities exposed by the package.a Not directly affiliated with ts-morph.

Installation

npm install ts-morph-utils --dev

yarn add -D ts-morph-utils

Utilities

morphDeclarationToRaw

Transforms a TypeScript declaration into its raw value. Useful in case you want to manipulate the object before writing it back to file.

Options:

• omit: any object keys you wish to omit from the transformed object
• resolveImports: whether to resolve imports. Passing false will simply null any external declarations which can't be reduced.
• reduceEnums: reduce enums or not. Passing false will add the enums to the externals as local statements.
• ignoreFunctions: passing false will replace function declarations with null

getPropertyFromConstructor

Retrieves a property from a class constructor.

getPropertyInInheritance

Finds a property in a class inheritance chain.

getMethodInInheritance

Finds a method in a class inheritance chain.

externalsToWritableDeclarations

Converts external definitions to writable declarations.

resolveExternalImport

Resolves an external import statement for a given identifier.

resolveExternalNodes

Resolves external nodes within a declaration.

resolveIdentifierValue

Returns a writable local statement and it's dependencies for a given identifier

writeReducedDeclaration

Writes a reduced declaration to a source file.

writeLocalStatements

Writes local statements to a source file.

writeImports

Writes import declarations to a source file.

writeExternals

Writes external definitions to a source file.

writeStatements

Writes statements to a source file.

getFunctionDeclaration

Retrieves a function declaration from a morphed string.

getExternalIdentifier

Gets an external identifier from a morphed string.

Usage

Example usage of some of the utilities.

import { morphDeclarationToRaw, writeMorphedDeclaration, writeExternals } from 'ts-morph-utils';

// context is used for external import declarations, to keep track of what has already been imported
const context = [];

const [valueOne, externalsOne] = morphDeclarationToRaw(someNode, project, context, {
  omit: [keyToOmit], // any object keys you want to omit
  resolveImports: true, // will populate the externalsOne array with import declarations from node_modules
  reduceEnums: true,
  ignoreFunctions: false
});

const [valueTwo, externalsTwo] = morphDeclarationToRaw(someOtherNode, project, context);

// the object is "evaled" into memory, so you can just read it's values
console.info(typeof valueOne.propertyOne === 'number');

// you can modify before writing it to file
valueOne.propertyTwo = 'new value';

// merge externals declaration so imports are not duplicated
const externals = new Set([...externalsOne, ...externalsTwo]);

// write the imports/externals to the source file
writeExternals(externals, sourceFile);

// write the reduced declarations to the source file
sourceFile.addVariableStatement({
  declarationKind: VariableDeclarationKind.Const,
  declarations: [
    {
      name: 'VALUE_ONE',
      initializer: (writer) => writeMorphedDeclaration(writer, valueOne, 0, 10),
      type: 'YOUR_TYPE'
    },
    {
      name: 'VALUE_TWO',
      type: 'YOUR_TYPE',
      initializer: (writer) => writeMorphedDeclaration(writer, valueTwo, 0, 6)
    }
  ]
});

Caveats

• This package still has some limitations, so use with caution.
• this is not supported in every context
• If a declaration depends on an external import, like a value from node_modules, that value will not be morphed, but instead added to the externals array. You can then write the externals to the source file with writeExternals.
• Functions are saved as strings and the writer utilities in the package will be able to write them back to file. You can eval the functions if you really, really need to, but I would not recommend it. eval is slow, and the functions may depend on variables/other functions outside their scope.