In most cases the string of characters

var str = 'asdkfjkdsfjisdjfsdkajfkasjflasdjf';
function fn(str){

    var obj = {};
    for(var i=0;i<str.length;i++){
        if(obj[str.charAt(i)]){
            obj[str.charAt(i)]++
        }
        else{
            obj[str.charAt(i)] =1;
        }
    }

    let num=0;
    let char="";
    for(var key in obj){
        if(obj[key]>num){
            num=obj[key];
            char=key;
        }
    }

    console.log(`单词是 ${char} 最多的数 ${num}`);

}
fn(str);