add(server.tests.test2): 添加实验2的内容，将pdf里面标重要的进行提取出来

Server/tests/test2/important/every.js

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+//  every(callbackFn)
+
+const stus = [{ name: '张三', score: 59 }, { name: '老钟', score: 95 }];
+let rst = stus.every((item) => {
+    return item.score >= 60
+})
+console.log(rst)
+
+/*
+# node every.js 
+false
+*/

Server/tests/test2/important/filter.js

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+// filter(callbackFn)
+
+const stus = [
+    { name: '张三', score: 59 },
+    { name: '老钟', score: 95 },
+    { name: 'SB', score: 80 }
+];
+
+// 筛选所有 score >= 60 的信息
+const rst = stus.filter(item => { return item.score >= 60 })
+console.log(rst)
+
+// 浅表拷贝，rst[0]的修改，会导致stus中对应数据的修改
+rst[0].score = 100
+console.log(stus)
+
+/*
+# node filter.js 
+[ { name: '老钟', score: 95 }, { name: 'SB', score: 80 } ]
+[
+  { name: '张三', score: 59 },
+  { name: '老钟', score: 100 },
+  { name: 'SB', score: 80 }
+]
+*/

Server/tests/test2/important/find.js

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+// find(callbackFn)
+
+const stus = [
+    { name: '张三', score: 59 },
+    { name: '老钟', score: 95 },
+    { name: 'SB', score: 80 }
+];
+
+// 筛选第一个 score >= 60 的信息
+const rst = stus.find(item => { return item.score >= 60 })
+console.log(rst)
+
+// 浅表拷贝，rst的修改，会导致stus中对应数据的修改
+rst.score = 100
+console.log(stus)
+
+/*
+# node find.js
+{ name: '老钟', score: 95 }
+[
+  { name: '张三', score: 59 },
+  { name: '老钟', score: 100 },
+  { name: 'SB', score: 80 }
+]
+*/

Server/tests/test2/important/findIndex.js

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+//  findIndex(callbackFn)
+
+const stus = [
+    { name: '张三', score: 59 },
+    { name: '老钟', score: 95 },
+    { name: 'SB', score: 80 }
+];
+
+// 返回第1个满足 score >= 60 条件的索引
+const rst = stus.findIndex(item => { return item.score >= 60 })
+console.log(rst)
+
+/*
+# node findIndex.js 
+1
+*/

Server/tests/test2/important/reduce.js

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+// arr.reduce(
+//     callback(accumulator, currentValue[, currentIndex[, array]])
+//     [, initialValue]
+// )
+
+const data1 = [1, 2, 3, 4, 5];
+// 没有使用初始值，则 sum 被初始为 1，cur从2开始, ..., ...
+let rst1 = data1.reduce((sum, cur) => {
+    return sum += cur
+})
+console.log(rst1)
+
+const data2 = [1, 2, 3, 4, 5];
+// 为初始值【1】，则temp被初始为【1】，cur从1开始, ..., ...
+let rst2 = data2.reduce((temp, cur) => {
+    return temp *= cur
+}, 1)
+console.log(rst2);
+
+const fruits = ['apple', 'banana', 'apple', 'banana', 'apple'];
+const rst3 = fruits.reduce((acc, cur) => {
+    if (!acc[cur])
+        acc[cur] = 1;
+    else
+        acc[cur]++;
+    return acc;
+}, {});
+console.log(rst3);
+
+const people = [
+    { name: 'zs', age: 25 },
+    { name: 'ls', age: 30 },
+    { name: 'ww', age: 25 },
+    { name: 'sb', age: 30 }
+];
+// 按年龄进行汇总，acc初始为{}，cur从zs这条数据开始
+const rst4 = people.reduce((acc, cur) => {
+    const age = cur.age;
+    if (!acc[age])
+        acc[age] = [];
+    acc[age].push(cur);
+    return acc;
+}, {});
+console.log(rst4);
+
+/*
+# node reduce.js 
+15
+120
+{ apple: 3, banana: 2 }
+{
+  '25': [ { name: 'zs', age: 25 }, { name: 'ww', age: 25 } ],
+  '30': [ { name: 'ls', age: 30 }, { name: 'sb', age: 30 } ]
+}
+*/

Server/tests/test2/important/slice.js

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+// let rst = array.slice([start[, end]]);
+
+const animals = ["ant", "bison", "camel", "duck", "elephant"];
+
+console.log(animals.slice(2))
+console.log(animals.slice(-2))
+console.log(animals.slice(2, 4))
+
+/*
+# node slice.js 
+[ 'camel', 'duck', 'elephant' ]
+[ 'duck', 'elephant' ]
+[ 'camel', 'duck' ]
+*/

Server/tests/test2/important/some.js

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+// some(callbackFn)
+
+const stus = [{ name: '张三', score: 59 }, { name: '老钟', score: 95 }];
+let rst = stus.some((item) => {
+    return item.score < 60
+})
+
+// 是否存在不及格的学生
+console.log(rst)
+
+
+/*
+# node some.js
+true
+*/

Server/tests/test2/important/sort.js

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+const data1 = [1, 30, 4, 20, 10]
+data1.sort()
+console.log(data1)
+
+// arr.sort(
+//     function (a, b) {...}
+// )
+
+const data2 = [1, 30, 4, 20, 10]
+// 升序排列
+data2.sort((a, b) => a - b)
+console.log(data2)
+
+const data3 = [1, 30, 4, 20, 10]
+// 降序排列
+data3.sort((a, b) => b - a)
+console.log(data3)
+
+const data4 = [
+    { name: 'zs', age: 28, score: 90 },
+    { name: 'ls', age: 38, score: 70 },
+    { name: 'sb', age: 18, score: 70 }
+]
+data4.sort((a, b) => {
+    return a.age - b.age
+})
+console.log(data4)
+
+data4.sort((a, b) => {
+    // 先按分数升序
+    let scoreRst = a.score - b.score
+    // 如果分数相同
+    if (scoreRst == 0)
+        // 按年龄降序
+        return b.age - a.age
+    return scoreRst
+})
+console.log(data4)
+
+/*
+# node sort.js 
+[ 1, 10, 20, 30, 4 ]
+[ 1, 4, 10, 20, 30 ]
+[ 30, 20, 10, 4, 1 ]
+[
+  { name: 'sb', age: 18, score: 70 },
+  { name: 'zs', age: 28, score: 90 },
+  { name: 'ls', age: 38, score: 70 }
+]
+[
+  { name: 'ls', age: 38, score: 70 },
+  { name: 'sb', age: 18, score: 70 },
+  { name: 'zs', age: 28, score: 90 }
+]
+*/

Server/tests/test2/important/splice.js

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+// splice(start)
+// splice(start, deleteCount)
+// splice(start, deleteCount, item1, ...)
+
+const datas = ["aa", "bb", "cc"];
+console.log(datas.splice(1))
+console.log(datas)
+
+console.log(datas.splice(1, 1))
+console.log(datas)
+
+console.log(datas.splice(1, 0, "xx", "yy"))
+console.log(datas)
+
+console.log(datas.splice(1, 1, "xx"))
+console.log(datas)
+
+/*
+# node splice.js 
+[ 'bb', 'cc' ]
+[ 'aa' ]
+[]
+[ 'aa' ]
+[]
+[ 'aa', 'xx', 'yy' ]
+[ 'xx' ]
+[ 'aa', 'xx', 'yy' ]
+*/

Server/tests/test2/important/unshift.js

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+// let len = array.unshift(element1, ..., elementN);
+
+const animals = ["pigs"]
+let rst = animals.unshift("dogs", "cats")
+console.log(rst)
+console.log(animals)
+
+/*
+# node unshift.js 
+3
+[ 'dogs', 'cats', 'pigs' ]
+*/