在jquery和ecmascript6中获得最高的属性号

Question

trying to get the max value for all selects with the same data attribute. but receiving the error

{ "message": "Uncaught TypeError: undefined is not a function",
"filename": " https://stacksnippets.net/js ", "lineno": 37, "colno": 34 }

please run snippet below I would like it to console out 3 as that is the highest responsegroupnumber with a question.id of 1

 $(document).ready(function() { let question = { Id: 1 }; let responseGroupNumber = Math.max(...$(`select[data-questionid = ${question.Id}]`) .map(x => $(x) .attr('data-responsegroupnumber'))); console.log(responseGroupNumber); }); 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <select data-questionid="1" data-responsegroupnumber="1"> <option>one</option> <option>two</option> <option>three</option> </select> <select data-questionid="1" data-responsegroupnumber="2"> <option>one</option> <option>two</option> <option>three</option> </select> <select data-questionid="1" data-responsegroupnumber="3"> <option>one</option> <option>two</option> <option>three</option> </select> 

Answer 1

You need to use the jQuery .get() function before mapping :

If you don't, you'll be using jQuery .map() method instead of Array#map

 $(document).ready(function() { let question = { Id: 1 }; let responseGroupNumber = Math.max(...$(`select[data-questionid = ${question.Id}]`).get().map(x => $(x).attr('data-responsegroupnumber'))); console.log(responseGroupNumber); }); 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <select data-questionid="1" data-responsegroupnumber="1"> <option>one</option> <option>two</option> <option>three</option> </select> <select data-questionid="1" data-responsegroupnumber="2"> <option>one</option> <option>two</option> <option>three</option> </select> <select data-questionid="1" data-responsegroupnumber="3"> <option>one</option> <option>two</option> <option>three</option> </select> 

Answer 2

Another possible implementation could be:

$(document).ready(function() {
 let question = {
   Id: 1
 };

 var selects = $(`select[data-questionid=${question.Id}]`).toArray();
 var dataGroupNumber = selects.map(select => ($(select).attr('data- 
   responsegroupnumber')));

let responseGroupNumber = Math.max.apply(null, dataGroupNumber);
console.log(responseGroupNumber);
});

Math.max.apply(null, dataGroupNumber) instead of spread the array inside the Math.max( ... );