字符串中出现次数最多的字符及其出现的次数

<script>
			let testStr = 'helloworld';
			let i;
			let tempObj = {};
			for (i = 0; i < testStr.length; i++) {
				let charAt = testStr.charAt(i); //相当于挨个遍历字符串字符，将字符作为key,出现的次数作为value类似java中的map
				if (tempObj[charAt]) {
					tempObj[charAt]++;
				} else {
					tempObj[charAt] = 1;
				}
			}
			// console.log(tempObj);
			//循环遍历对象找到最大数
			let max = 0; //初始化一个最大数
			let maxStr;
			let obj;
			for (obj in tempObj) {
				if (tempObj[obj] > max) {
					max = tempObj[obj];
					maxStr = obj;
				}
			}
			console.log(maxStr + ':' + max);
		</script>