From fcc6ef2a49fb98d726dec1f3b2edc8f7990fea3d Mon Sep 17 00:00:00 2001
From: Hanzhang ma <harvey.ma@eng2move.com>
Date: Sat, 22 Jun 2024 23:54:56 +0200
Subject: [PATCH] add 6.2 and 6.3

---
 6.2RestSpread/t.js    | 47 +++++++++++++++++++++++++++++++++++++++++++
 6.3variablescope/t.js | 39 +++++++++++++++++++++++++++++++++++
 2 files changed, 86 insertions(+)
 create mode 100644 6.2RestSpread/t.js
 create mode 100644 6.3variablescope/t.js

diff --git a/6.2RestSpread/t.js b/6.2RestSpread/t.js
new file mode 100644
index 0000000..0b85a4f
--- /dev/null
+++ b/6.2RestSpread/t.js
@@ -0,0 +1,47 @@
+console.log("Rest and Spread Operator");
+
+console.log("Rest Operator");
+// Rest Operator
+
+function sumAll(...args){
+    let sum = 0;
+    for(let arg of args){
+        sum += arg;
+    }
+    return sum;
+}
+
+console.log(sumAll(1,2,3,4,5));
+
+function showName(firstName, lastName, ...titles) {
+    console.log( firstName + ' ' + lastName ); // Julius Caesar
+
+    // 剩余的参数被放入 titles 数组中
+    // i.e. titles = ["Consul", "Imperator"]
+    console.log( titles[0] ); // Consul
+    console.log( titles[1] ); // Imperator
+    console.log( titles.length ); // 2
+}
+
+showName("Julius", "Caesar", "Consul", "Imperator");
+
+console.log("Attention: Rest parameters should be at the end");
+console.log("Attention: Only one rest parameter is allowed");
+consoel.log("Attention: Arrow functions do not have 'arguments' object");
+
+console.log("Spread Operator");
+// Spread Operator
+let arr = [3, 5, 1];
+console.log(Math.max(arr)); // NaN
+console.log(Math.max(...arr)); // 5
+let arr1 = [1, -2, 3, 4];
+let arr2 = [8, 3, -8, 1];
+console.log(Math.max(...arr1, ...arr2)); // 8
+let merged = [0, ...arr1, 2, ...arr2];
+console.log(merged);
+
+console.log("Attention: Spread operator can be used to merge arrays");
+console.log("Attention: Spread operator can be used to convert string to array");
+console.log("Attention: Spread operator can be used to convert arguments to array");
+
+
diff --git a/6.3variablescope/t.js b/6.3variablescope/t.js
new file mode 100644
index 0000000..45be6bf
--- /dev/null
+++ b/6.3variablescope/t.js
@@ -0,0 +1,39 @@
+
+function sum(a){
+    return function(b){
+        return a + b;
+    }
+}
+
+console.log(sum(1)(2));
+console.log(sum(5)(-1));
+
+
+function byField(Field){
+    return (a,b) => a[Field] > b[Field]? 1: -1;
+}
+
+
+function makeArmy() {
+    let shooters = [];
+
+    let i = 0;
+    while (i < 10) {
+        let id = i;
+        let shooter = function() { // 创建一个 shooter 函数，
+            console.log( id ); // 应该显示其编号
+        };
+        shooters.push(shooter); // 将此 shooter 函数添加到数组中
+        i++;
+    }
+
+    // ……返回 shooters 数组
+    return shooters;
+}
+
+let army = makeArmy();
+
+// ……所有的 shooter 显示的都是 10，而不是它们的编号 0, 1, 2, 3...
+army[0](); // 编号为 0 的 shooter 显示的是 10
+army[1](); // 编号为 1 的 shooter 显示的是 10
+army[2](); // 10，其他的也是这样。