From fc4e38cb45020fba2ea53f907fbfa8458fafb424 Mon Sep 17 00:00:00 2001
From: LeoEatle <liuyitao811@hotmail.com>
Date: Sun, 19 Jan 2020 17:17:56 +0800
Subject: [PATCH] add intersection types

---
 README.md                       |  1 +
 SUMMARY.md                      |  1 +
 advanced/README.md              |  1 +
 advanced/declaration-merging.md |  2 +-
 advanced/further-reading.md     |  2 +-
 advanced/intersection-types.md  | 45 +++++++++++++++++++++++++++++++++
 6 files changed, 50 insertions(+), 2 deletions(-)
 create mode 100644 advanced/intersection-types.md

diff --git a/README.md b/README.md
index 0fea6cab..362e8024 100644
--- a/README.md
+++ b/README.md
@@ -81,6 +81,7 @@ TypeScript 虽然有[官方手册][Handbook]及其[非官方中文版][中文手
   - [类与接口](advanced/class-and-interfaces.md)
   - [泛型](advanced/generics.md)
   - [声明合并](advanced/declaration-merging.md)
+  - [交叉类型](advanced/intersections-types.md)
   - [扩展阅读](advanced/further-reading.md)
 - [工程](engineering/README.md)
   - [代码检查](engineering/lint.md)
diff --git a/SUMMARY.md b/SUMMARY.md
index 5c876ac6..b9a166c9 100644
--- a/SUMMARY.md
+++ b/SUMMARY.md
@@ -25,6 +25,7 @@
   - [类与接口](advanced/class-and-interfaces.md)
   - [泛型](advanced/generics.md)
   - [声明合并](advanced/declaration-merging.md)
+  - [交叉类型](advanced/intersections-types.md)
   - [扩展阅读](advanced/further-reading.md)
 - [工程](engineering/README.md)
   - [代码检查](engineering/lint.md)
diff --git a/advanced/README.md b/advanced/README.md
index f969babf..3948e023 100644
--- a/advanced/README.md
+++ b/advanced/README.md
@@ -10,6 +10,7 @@
 - [类与接口](class-and-interfaces.md)
 - [泛型](generics.md)
 - [声明合并](declaration-merging.md)
+- [交叉类型](advanced/intersections-types.md)
 - [扩展阅读](further-reading.md)
 
 ---
diff --git a/advanced/declaration-merging.md b/advanced/declaration-merging.md
index f0d50dcd..d4a1b02f 100644
--- a/advanced/declaration-merging.md
+++ b/advanced/declaration-merging.md
@@ -99,4 +99,4 @@ interface Alarm {
 ---
 
 - [上一章：泛型](generics.md)
-- [下一章：扩展阅读](further-reading.md)
+- [下一章：交叉类型](intersections-types.md)
diff --git a/advanced/further-reading.md b/advanced/further-reading.md
index 7121ddf9..0b49de0b 100644
--- a/advanced/further-reading.md
+++ b/advanced/further-reading.md
@@ -23,5 +23,5 @@
 
 ---
 
-- [上一章：声明合并](declaration-merging.md)
+- [上一章：交叉类型](intersections-types.md)
 - [下一章：工程](../engineering/README.md)
diff --git a/advanced/intersection-types.md b/advanced/intersection-types.md
new file mode 100644
index 00000000..65f657d9
--- /dev/null
+++ b/advanced/intersection-types.md
@@ -0,0 +1,45 @@
+# 交叉类型
+
+交叉类型（Intersection Types）和联合类型（Union Types）相反，表示该取值的类型属于多个类型的交集，可以使用的属性为这几个类型属性的并集。
+
+## 简单的例子
+
+```ts
+interface A {
+    a: string
+}
+
+interface B {
+    b: string
+}
+
+let test: A & B = {
+    a: 'test a',
+    b: 'test b'
+}
+```
+
+交叉类型使用 `&` 分隔每个类型。
+
+这里 `let test: A & B` 的含义是，`test` 的类型同时属于 `A` 和 `B`，并且同时具有两者的属性 `a` 和 `b`。
+
+## 使用联合类型定义 extend object
+
+```ts
+function extend<First, Second>(first: First, second: Second): First & Second {
+    const result: Partial<First & Second> = {
+        ...first,
+        ...second
+    };
+    return result as First & Second;
+}
+```
+
+## 参考
+
+- [Advanced Types # Intersection Types](http://www.typescriptlang.org/docs/handbook/advanced-types.html#intersection-types)([中文版](https://zhongsp.gitbooks.io/typescript-handbook/content/doc/handbook/Advanced%20Types.html#%E4%BA%A4%E5%8F%89%E7%B1%BB%E5%9E%8B))
+
+---
+
+- [上一章：声明合并](declaration-merging.md)
+- [下一章：扩展阅读](further-reading.md)