tspatterns.js

"use strict";

const ts = require("typescript");

const getLine =
      (sourceFile, node) => sourceFile
      .getLineAndCharacterOfPosition(node.getStart(sourceFile))
      .line + 1; // + 1 because it is 0-based by default.;

exports.parse = function parse(filename, data) {
  const sourceFile = ts.createSourceFile(filename, data);
  const { statements } = sourceFile;
  for (let statementsIx = 0; statementsIx < statements.length; ++statementsIx) {
    const statement = statements[statementsIx];
    if (statement.kind !== ts.SyntaxKind.VariableStatement ||
        statement.declarationList.kind !==
        ts.SyntaxKind.VariableDeclarationList) {
      continue; // eslint-disable-line no-continue
    }

    const decls = statement.declarationList.declarations;
    for (let declsIx = 0; declsIx < decls.length; ++declsIx) {
      const node = decls[declsIx];
      const { initializer } = node;
      if (node.kind === ts.SyntaxKind.VariableDeclaration &&
          node.name.text === "version" &&
          initializer.kind === ts.SyntaxKind.StringLiteral) {
        // Bingo!
        return {
          version: initializer.text,
          line: getLine(sourceFile, initializer),
        };
      }
    }
  }

  return undefined;
};