js 数组反转 删除数组重复 字符串重复字符的个数 替换字符串字符

    <script>
        //数组反转
        function arrayReverse(arr) {
            if (Array.isArray(arr)) {
                var newArr = []
                for (var i = arr.length - 1; i >= 0; i--) {
                    newArr.push(arr[i])
                }
                return newArr
            } else {
                console.log("error")
            }
        }
        console.log(arrayReverse([1, 4, 6, 32, 9]))
        //删除数组重复
        function delRepArr(arr) {
            var newArr = []
            for (var i = 0; i < arr.length; i++) {
                if (newArr.indexOf(arr[i]) === -1) {
                    newArr.push(arr[i])
                }
            }
            return newArr
        }
        console.log(delRepArr([2, 45, 1, 5, 2, 54, 7, 23, 45, 5, 1]))
        //查字符串重复字符的个数 
        var ss = "awbwea234abwera234a"
        var index = ss.indexOf('a')
        var num = 0
        while (index != -1) {
            console.log(index);
            num++;
            index = ss.indexOf('a', index + 1)
        }
        console.log('a count' + num)
        //字符串字符重复个数 并且最多的字符及其重复数
        var str = "awbwea234abwera234a"
        var obj = {}
        for (var i = 0; i < str.length; i++) {
            var ch = str.charAt(i)
            if (obj[ch]) {
                obj[ch] = obj[ch] + 1
            } else {
                obj[ch] = 1
            }
        }
        var max = 0
        var maxchr = ''
        for (var s in obj) {
            if (obj[s] > max) {
                max = obj[s]
                maxchr = s
            }

        }
        console.log("最多字符：" + maxchr + "出现次数" + max)
        //替换字符串字符
        var str1 = "awbwea234abwera234a"
        while (str1.indexOf('a') != -1) {
            str1 = str1.replace('a', '*')
        }
        console.log(str1)
    </script>