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 () {
    let str = await readline();
    let char = await readline();
    let count = 0 ;

    if(char !== ""){
        let strArr = str.split('');
        let lowercaseStrArr = strArr.map(item => item.toLowerCase());
        let lowercaseChar = char.toLowerCase();

        let index = lowercaseStrArr.indexOf(lowercaseChar);
        while(index !== -1){
            count ++;
            index = lowercaseStrArr.indexOf(lowercaseChar, index+1);
        }

    }

    console.log(count);
}()