checkRepeat: function (arr) {
    let arrlist = [];
    let list = [];
    let str = '';
    for (let i = 0; i < arr.length; i++) {
        let hasRead = false;
        for (let k = 0; k < list.length; k++) {
            if (i === list[k]) {
                hasRead = true;
            }
        }
        if (hasRead) {
            continue;
        }
        let _index = i, haveSame = false;
        for (let j = i + 1; j < arr.length; j++) {
            if (arr[i] === arr[j]) {
                list.push(j);
                _index += "," + j;
                haveSame = true;
            }
        }
        if(_index.length > 1){
            arrlist = _index.split(',');
            for(let m of arrlist){
                str += '遊客' + (Number(m)+1) + '、';
            }
            str=str.substring(0,str.length-1);
            str += '身份證號重複;'
        }
    }
    if(str){
        layer.alert(str, {
            title: '提示'
        });
        console.log(str);
        return false;
    }else{
        return true;
    }
}
 

呼叫次函式即可