经过大量的研究，我还没有发现满足所有这些IF条件的正则表达式。代码工作得很好，但我认为可以用RegEx来简化它。
目标：对从1到9的正整数返回true，而不是以零开始。对于其他每个值返回false。
看一下

// Validation functions


function hasPeriod(s) {
  // Return true or false.
  // True if a period is entered at any point in time.
  return s.indexOf('.') > -1;
}
// See more... http://2ality.com/2014/05/is-integer.html
function isInteger(s) {
  // Return true or false.
  // True if the remainder of dividing it by 1 is 0.
  return s % 1 === 0;
}



// Bind keyup event to prep_work_item_input.
$('#input1').on('keyup', function (e) {

  // TRIM text input value on declaration...
  // May contain spaces...
  var input_value = $(this).val().trim();

  // Refresh text input after Trim!
  // Does not contain spaces
  $(this).val(input_value);

  // If text input is EMPTY after Trim...
  if (input_value.length == 0) {

    // Stop at this if and dont proceed.
    return false;

  } 

  // If a PERIOD is typed into text input at any point in time...
  if (hasPeriod(input_value)) {

    // Clear input
    $(this).val('');

    // Stop at this if and dont proceed.
    return false;

  }

  // If text input value is NOT an INTEGER...
  if (!isInteger(input_value)) {

    // Clear input
    $(this).val('');

    // Stop at this if and dont proceed.
    return false;
  }

  // If text input value IS an INTEGER but EQUAL to 0...
  if (input_value == 0) {

    // Clear input
    $(this).val('');

    // Stop at this if and dont proceed.
    return false;
  }

  // If text input value IS an INTEGER and also GREATER than 0...
  if (input_value > 0) {

    // If we have made this far... 
    // we probably have a real integer that is not zero.

    // We can finally begin to calculate

    input_value = parseInt(input_value);

    // random cost multiplier for this example
    var cost = parseFloat('0.78');

    // calculate subtotal...
    cost = input_value * cost;

    // Set prep_work_item_subtotal...        
    console.log(input_value + ' ' + 'SF' + ' / ' + ' $' + cost.toFixed(2));

  }

});

个字符