jQuery输入数字的倍数（键）

Question

How can I make an input element accept numbers only in multiples of 50?

I know we can specify step="50" as an attribute, but I would prefer a solution that is triggered by the keyup event .

I found this code, which prevents users from entering a number less than 50.

Question : How can I adjust this code so that only multiples of 50 can be entered ?

 $('#numberbox').keyup(function(){ if ($(this).val() < 50){ alert("Minimum Quantity: 50"); $(this).val('50'); } }); 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <input id="numberbox" type='number'> 

Answer 1

Use the modulo operator

var multiple = 50;

$('#numberbox').keyup(function(){
   if (parseInt($(this).val()) % multiple ) {
      alert("Only multiples of " + multiple + " allowed");
      $(this).val(multiple);
   }
});

Answer 2

You can use Remainder (%) to do this, check the example bellow.

The remainder operator returns the remainder left over when one operand is divided by a second operand. It always takes the sign of the dividend, not the divisor.

 $('#numberbox').keyup(function(){ if ($(this).val()%50==0){ $('#result').text($(this).val()+' is multiple of 50'); }else{ $('#result').text($(this).val()+' is not a multiple of 50'); } }); 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <input id="numberbox" type='number'> <span id='result'></span> 

Hope this helps.

Answer 3

I would prefer blur instead of keyup as keyup would keep on alerting. To know if it is multiple of 50 check a condition with modulo ie % like if parseInt($(this).val())%50 != 0

 $('#numberbox').blur(function(){ if (parseInt($(this).val())%50 != 0){ alert("Multiples of 50 should be entered"); $(this).val('50'); } }); 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <input id="numberbox" type='number'>