ts compiler api

ast

借助该api可以遍历ts文件的ast树做一些事情，例如代码检查。

[文档](Using the Compiler API · microsoft/TypeScript Wiki · GitHub (opens new window))

import { readFileSync } from "fs";
import * as ts from "typescript";

export function delint(sourceFile: ts.SourceFile) {
  delintNode(sourceFile);

  function delintNode(node: ts.Node) {
    switch (node.kind) {
      case ts.SyntaxKind.ForStatement:
      case ts.SyntaxKind.ForInStatement:
      case ts.SyntaxKind.WhileStatement:
      case ts.SyntaxKind.DoStatement:
        if ((node as ts.IterationStatement).statement.kind !== ts.SyntaxKind.Block) {
          report(
            node,
            'A looping statement\'s contents should be wrapped in a block body.'
          );
        }
        break;

      case ts.SyntaxKind.IfStatement:
        const ifStatement = node as ts.IfStatement;
        if (ifStatement.thenStatement.kind !== ts.SyntaxKind.Block) {
          report(ifStatement.thenStatement, 'An if statement\'s contents should be wrapped in a block body.');
        }
        if (
          ifStatement.elseStatement &&
          ifStatement.elseStatement.kind !== ts.SyntaxKind.Block &&
          ifStatement.elseStatement.kind !== ts.SyntaxKind.IfStatement
        ) {
          report(
            ifStatement.elseStatement,
            'An else statement\'s contents should be wrapped in a block body.'
          );
        }
        break;

      case ts.SyntaxKind.BinaryExpression:
        const op = (node as ts.BinaryExpression).operatorToken.kind;
        if (op === ts.SyntaxKind.EqualsEqualsToken || op === ts.SyntaxKind.ExclamationEqualsToken) {
          report(node, 'Use \'===\' and \'!==\'.');
        }
        break;
    }

    ts.forEachChild(node, delintNode);
  }

  function report(node: ts.Node, message: string) {
    const { line, character } = sourceFile.getLineAndCharacterOfPosition(node.getStart());
    console.log(`${sourceFile.fileName} (${line + 1},${character + 1}): ${message}`);
  }
}

const fileNames = process.argv.slice(2);
fileNames.forEach(fileName => {
  // Parse a file
  const sourceFile = ts.createSourceFile(
    fileName,
    readFileSync(fileName).toString(),
    ts.ScriptTarget.ES2015,
    /*setParentNodes */ true
  );

  // delint it
  delint(sourceFile);
});