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
    let lineNum = 0;
    let tokens = "";
    let char = "";    
    while ((line = await readline())) {
        lineNum++;
        if (lineNum == 1) {
            tokens = line.trim();
            if(tokens.length==0){
                console.log("请输入第一行字符串")
                return
            }
            if(tokens.length>1000){
                console.log("第一行字符串长度超出限制")
                return
            }
        } else if (lineNum == 2) {
            char = line.trim();
            if(char.length==0){
                console.log("请输入第二行字符")
                return
            }
            if(char.length>1){
                console.log("第二行字符长度超出限制")
                return
            }
        }
    }
    let sum = 0;
    tokens.split(" ").forEach((item) => {
        let count = 0;
        item.toLowerCase()
            .split("")
            .forEach((itm) => {
                if (itm == char.toLowerCase()) {
                    count++;
                }
            });
        sum += count;
    });

    console.log(sum);
})();