js3-计算某字母出现次数

www.nowcoder.com/practice/a3…

var a = readline()
var b = readline()
var count = 0;
function HJ2(a,b){
    for(var i = 0;i<a.length;i++){
        if(a[i].toLowerCase()==b.toLowerCase()){
            count++
        }
    }
    console.log(count)
}
HJ2(a,b)