题解 | 计算某字符出现次数

const rl = require("readline").createInterface({ input: process.stdin });
var iter = rl[Symbol.asyncIterator]();
const readline = async () => (await iter.next()).value;

void async function () {
    // Write your code here
    const theString  = await readline()//入参一，字符串;
    const theInput  = await readline()//入参二，单个字符;
    let theLength = 0
    for(let index = 0; index<theString.length;index++){
		//判断是否符合题目要求;如果不允许使用正则，则用哈希表来处理。单个字符全等于其字身，或者等于它自己。如theString[index]===({a:A,b:B})[theInput] 或 theString[index]===theInput。
        if(new RegExp(`^${theInput}$`,'i').test(theString[index])){
            theLength = theLength + 1
        }
    }
    console.log(theLength)
}()