typescript 2.7 编译选项详解

// leon.js
export let author = 'leon'

// index.ts
import { author } from './leon'
console.log(author);

// leon.ts
export let author = 'leon'

// index.ts
import * as leon from './leon' // 这句选项怎么变都对

console.log(leon.author);

export default function test() {
  return 1
  let a = 1000  // error TS7027: Unreachable code detected.
}

loop1:
for (let i = 0; i < 3; i++) {
   loop2:         // error TS7028: Unused label
   for (let j = 0; j < 3; j++) {
      if (i == 1 && j == 1) {
         continue loop1;
      }
      console.log("i = " + i + ", j = " + j);
   }
}

// tsc index.ts
var sum = 015  // error TS1121: Octal literals are not allowed in strict mode.
+ 197
+ 142;

// index.ts
import test from 'test'

// test.ts
let test = 1

export default test

// -- checkJs true
// index.js
import { a } from 'test'

a('1324') // error TS2345: Argument of type '"1324"' is not assignable to parameter of type 'number'.

// test.ts
export function a(i: number) {
  return i
}

Files:            2
Lines:        19890
Nodes:        91623
Identifiers:  31621
Symbols:      24094
Types:         6581
Memory used: 60631K
I/O read:     0.00s
I/O write:    0.00s
Parse time:   0.29s
Bind time:    0.12s
Check time:   0.80s
Emit time:    0.02s
Total time:   1.23s

let a = [1, 2, 3]

let b = [4, ...a]

var a = [1, 2, 3];
var b = [4].concat(a);

var __read = (this && this.__read) || function (o, n) {
    var m = typeof Symbol === "function" && o[Symbol.iterator];
    if (!m) return o;
    var i = m.call(o), r, ar = [], e;
    try {
        while ((n === void 0 || n-- > 0) && !(r = i.next()).done) ar.push(r.value);
    }
    catch (error) { e = { error: error }; }
    finally {
        try {
            if (r && !r.done && (m = i["return"])) m.call(i);
        }
        finally { if (e) throw e.error; }
    }
    return ar;
};
var __spread = (this && this.__spread) || function () {
    for (var ar = [], i = 0; i < arguments.length; i++) ar = ar.concat(__read(arguments[i]));
    return ar;
};
var a = [1, 2, 3];
var b = __spread([4], a);

export let a = 100
let b = 200
export default a

"use strict";
exports.__esModule = true;
exports.a = 100;
var b = 200;
exports["default"] = exports.a;

// Test.ts
let a = 1
export default a

import a from './test' // 导入小写，没问题
import b from './Test' // 再导入大写，报错。 error TS1149: File name '/Users/leon/Documents/git/typescript-options/forceConsistentCasingInFileNames/Test.ts' differs from already included file name '/Users/leon/Documents/git/typescript-options/forceConsistentCasingInFileNames/test.ts' only in casing.

let b = {
  name: 'leon'
}

let a = {
  age: 10,
  ...b
}

var __assign = (this && this.__assign) || Object.assign || function(t) {
    for (var s, i = 1, n = arguments.length; i < n; i++) {
        s = arguments[i];
        for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p))
            t[p] = s[p];
    }
    return t;
};
var b = {
    name: 'leon'
};
var a = __assign({ age: 10 }, b);

//# sourceMappingURL= xxxxxxx

sourceMappingURL = xxxxx

// index.ts
function a() {
}

// error TS1208: Cannot compile namespaces when the '--isolatedModules' flag is provided.

error TS5053: Option 'declaration' cannot be specified with option 'isolatedModules'.

export function a() {
  return (
    <text>a</text>
  )
}

// --jsx "React"
"use strict";
exports.__esModule = true;
function a() {
    return (React.createElement("text", null, "a"));
}
exports.a = a;

// --jsx "Preserve"
"use strict";
exports.__esModule = true;
function a() {
    return (<text>a</text>);
}
exports.a = a;

export function a() {
  return (
    <text>a</text>
  )
}

// --jsx "React" --jsxFactory h
// 请与上个例子对比。
"use strict";
exports.__esModule = true;
function a() {
    return (h("text", null, "a"));
}
exports.a = a;

export default function test() {
  let a = 1
  let b = new Promise(resolve => {
    resolve(1)
  })
  return a
}

// tsc lib/index.ts --lib ES5
// error TS2693: 'Promise' only refers to a type, but is being used as a value here.

// tsc lib/index.ts --lib ES6
// build pass

  - maxNodeModuleJsDepth
    - index.ts
    - node_modules
      - test1
        - index.js
        - node_modules
          - test2
            - index.js

  // maxNodeModuleJsDepth/index.ts
  import a from 'test1' // maxNodeModuleJsDepth设置成什么，这句总是对的
  import b from 'test2' // 这句总是错的。

// index.ts
export function test() {
  return 'hello'
}

// --module CommonJs

exports.__esModule = true;
function test() {
    return 'hello';
}
exports.test = test;

// --module AMD

define(["require", "exports"], function (require, exports) {
    "use strict";
    exports.__esModule = true;
    function test() {
        return 'hello';
    }
    exports.test = test;
});

// -module system
System.register([], function (exports_1, context_1) {
    "use strict";
    var __moduleName = context_1 && context_1.id;
    function test() {
        return 'hello';
    }
    exports_1("test", test);
    return {
        setters: [],
        execute: function () {
        }
    };
});

// -module UMD
(function (factory) {
    if (typeof module === "object" && typeof module.exports === "object") {
        var v = factory(require, exports);
        if (v !== undefined) module.exports = v;
    }
    else if (typeof define === "function" && define.amd) {
        define(["require", "exports"], factory);
    }
})(function (require, exports) {
    "use strict";
    exports.__esModule = true;
    function test() {
        return 'hello';
    }
    exports.test = test;
});

// -module es6 or es2015 or esnext

export function test() {
    return 'hello';
}

// index.ts
export function test() {
  return new Promise(resolve => {
    resolve(1)
  })
}

// --target es3
"use strict";
var __assign = (this && this.__assign) || Object.assign || function(t) {
    for (var s, i = 1, n = arguments.length; i < n; i++) {
        s = arguments[i];
        for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p))
            t[p] = s[p];
    }
    return t;
};
exports.__esModule = true;
function test() {
    return new Promise(function (resolve) {
        var a = {
            a: 1,
            b: 2
        };
        resolve(__assign({ c: 3 }, a));
    });
}
exports.test = test;

// --target es5
"use strict";
var __assign = (this && this.__assign) || Object.assign || function(t) {
    for (var s, i = 1, n = arguments.length; i < n; i++) {
        s = arguments[i];
        for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p))
            t[p] = s[p];
    }
    return t;
};
Object.defineProperty(exports, "__esModule", { value: true });
function test() {
    return new Promise(function (resolve) {
        var a = {
            a: 1,
            b: 2
        };
        resolve(__assign({ c: 3 }, a));
    });
}
exports.test = test;

// --target es6
export function test() {
    return new Promise(resolve => {
        let a = {
            a: 1,
            b: 2
        };
        resolve(Object.assign({ c: 3 }, a));
    });
}

// --target esnext
export function test() {
    return new Promise(resolve => {
        let a = {
            a: 1,
            b: 2
        };
        resolve({
            c: 3,
            ...a
        });
    });
}

export function test() {
  let a = {
    a: 1
  }
  return {
    b: 2,
    ...a
  }
}

// --noEmitHelpers true
export function test() {
    var a = {
        a: 1
    };
    return __assign({ b: 2 }, a);
}

// --noEmitHelpers false
var __assign = (this && this.__assign) || Object.assign || function(t) {
    for (var s, i = 1, n = arguments.length; i < n; i++) {
        s = arguments[i];
        for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p))
            t[p] = s[p];
    }
    return t;
};
export function test() {
    var a = {
        a: 1
    };
    return __assign({ b: 2 }, a);
}

export let a = 1

switch(a) {
  case 1:
    console.log(a)  // error TS7029: Fallthrough case in switch.

  case 2:
}

// --noImplicitAny true
function a1(b) {  // error TS7006: Parameter 'b' implicitly has an 'any' type.
  return b
}

// --noImplicitReturns true
function a2(b) {  // 编译通过，与文档似乎不符
  if (b) {
    console.log(b)
    return b
  }
}

// --noImplicitThis true
function a1(b: any) { // error TS2683: 'this' implicitly has type 'any' because it does not have a type annotation.
  return this.b
}

// index.ts
/// <reference path="./my.d.ts" />

import { a } from './Test'

// my.d.ts
declare module A {
  export function test(number, string): any
}

// test.ts
export let a = 1

// tsc noResolve/index.ts  --listFiles

/Users/leon/.nvm/versions/node/v8.7.0/lib/node_modules/typescript/lib/lib.d.ts
noResolve/my.d.ts
/Users/leon/Documents/git/typescript-options/noResolve/Test.ts
noResolve/index.ts

// tsc noResolve/index.ts --noResolve --listFiles
noResolve/index.ts(3,19): error TS2307: Cannot find module './Test'.
/Users/leon/.nvm/versions/node/v8.7.0/lib/node_modules/typescript/lib/lib.d.ts
noResolve/index.ts

export function A() { // error TS6133: 'b' is declared but its value is never read.
  let a = 0  // error TS6133: 'a' is declared but its value is never read.
  return
}

// realIndex.ts
export let a = 1

// index.ts --> realIndex.ts

// 此选项并不影响 tesc index.ts 的编译

// ./test/index.ts
let a = 1

// tsc test/index.ts --outDir ./test/dist/ --rootDir .
生成 ./test/dist/test/index.js

// tsc test/index.ts --outDir ./test/dist/
生成 ./test/dist/index.js

// test.js
export let a = [1, ,2, 3]

// test.d.ts
export declare let a: number[];

// index.ts
import { a } from './test'
a[0] = '12'

error TS2322: Type '"12"' is not assignable to type 'number'.

class A {
  name: string
  age = 10

  constructor(age: number) { // error TS2564: Property 'name' has no initializer and is not definitely assigned in the constructor.
    this.age = age
  }
}

let a1: number = null       // error TS2322: Type 'null' is not assignable to type 'number'.
let a2: string = undefined  // error TS2322: Type 'undefined' is not assignable to type 'string'.

export class A {
  name: string
  age = 10

  constructor(age: number) {
    this.age = age
  }
}

let a: A = {
  name: 'leon',
  age: 30,
  gender: 'male'
}

// --suppressExcessPropertyErrors false
error TS2322: Type '{ name: string; age: number; gender: string; }' is not assignable to type 'A'.
Object literal may only specify known properties, and 'gender' does not exist in type 'A'.

//  --suppressExcessPropertyErrors true
pass

Module resolution kind is not specified, using 'NodeJs'.
Loading module as file / folder, candidate module location '/Users/leon/Documents/git/typescript-options/skipLibCheck/test', target file type'TypeScript'.
File '/Users/leon/Documents/git/typescript-options/skipLibCheck/test.ts' does not exist.
File '/Users/leon/Documents/git/typescript-options/skipLibCheck/test.tsx' does not exist.
File '/Users/leon/Documents/git/typescript-options/skipLibCheck/test.d.ts' exist - use it as a name resolution result.