如何只输入有限的字母 <input type=“text” /> 用jQuery？

Question

例如，仅允许输入数字：

<input type="text" id="target" />

Answer 1

Use the keypress() event. This example prevents characters that aren't digits (0 = 48, 9 = 57).

$(function() {
  $("#target").keypress(function(evt) {
    if (evt.which < 48 || evt.which > 57) {
      return false;
    }
  });
});

See this list of Javascript key codes .

Answer 2

var value = $('#target').val();

function isNumber ( n ) { return !isNaN( n ) }

isNumber(value) // if its '3' then true
isNumber(value) // if 3 then true
isNumber(value) // if '' then false