第三节 示例

1.将一段字符串的英文文字倒过来

 <script>
        var str = "let's go home";
        /* s'tel og emoh */
        /* 
        1.将字符串分割为数组split(" ")
        ["let's","go","home"] 
        */
        /* [[l,e,t,',s],[g,o],[h,o,m,e]] */
        /* reverse */
        /* [[s,',t,e,l],[o,g],[e,m,o,h]] */
        /* join */
        /* ["s'tel","og","emoh"] */
        /* join */
        /* s'tel og emoh */

 <script>
        var str = "let's go home";
        var arr=str.split(" ");
        var newArr=arr.map(item=>{
        return item.aplit("")).reverse().join("")
        })
        console.log(new.Arr.join(" "))

2.只取对象里某一对象，放一个数组里

题目：

 var obj = [{name:"汪峰",age:10},{name:"赵雷",age:5},{name:"房东的猫",age:6}]
        /* 1.["汪峰","赵雷","房东的猫"] */
        /* 2. 汪峰/赵雷/房东的猫*/
 /* allName = "汪峰/赵雷/房东的猫" */

 var obj = [{name:"汪峰",age:10},{name:"赵雷",age:5},{name:"房东的猫",age:6}]
 var newArr = obj.map(item=>{
            return item.name
        })
        console.log(newArr.join("/"))

3. 天或tian 开头的 将city添加到一个数组中

 <script>
        var cities = [{spell:"tianmen",city:"天门"},{city:"天津",spell:"tianjin"},
            {spell:"tianshui",city:"天水"},{spell:"wuhan",city:"武汉"}
        ]
        /* var allCities =[] */
        var allCities = [];
        cities.forEach(item=>{
            if(item.spell.startsWith("tian") || item.city.startsWith("天")){
                allCities.push(item.city)
            }
        })
       console.log(allCities)
    </script>