步骤1:将HTML数字输入框与onchange事件挂钩

myHTMLNumberInput.onchange = setTwoNumberDecimal;

或者HTML代码

<input type="number" onchange="setTwoNumberDecimal" min="0" max="10" step="0.25" value="0.00" />

步骤2:编写setTwoDecimalPlace方法

function setTwoNumberDecimal(event) {
    this.value = parseFloat(this.value).toFixed(2);
}

您可以通过改变传递给toFixed()方法的值来改变小数点后的位数。请参阅MDN文档。

toFixed(2); // 2 decimal places
toFixed(4); // 4 decimal places
toFixed(0); // integer

步骤1:将HTML数字输入框与onchange事件挂钩

myHTMLNumberInput.onchange = setTwoNumberDecimal;

或者HTML代码

<input type="number" onchange="setTwoNumberDecimal" min="0" max="10" step="0.25" value="0.00" />

步骤2:编写setTwoDecimalPlace方法

function setTwoNumberDecimal(event) {
    this.value = parseFloat(this.value).toFixed(2);
}

您可以通过改变传递给toFixed()方法的值来改变小数点后的位数。请参阅MDN文档。

toFixed(2); // 2 decimal places
toFixed(4); // 4 decimal places
toFixed(0); // integer

如果有人正在寻找一个正则表达式，只允许数字与可选的2小数点后

^\d*(\.\d{0,2})?$

例如，我发现下面的解决方案相当可靠

HTML:

<input name="my_field" pattern="^\d*(\.\d{0,2})?$" />

JS / JQuery:

$(document).on('keydown', 'input[pattern]', function(e){
  var input = $(this);
  var oldVal = input.val();
  var regex = new RegExp(input.attr('pattern'), 'g');

  setTimeout(function(){
    var newVal = input.val();
    if(!regex.test(newVal)){
      input.val(oldVal); 
    }
  }, 1);
});

输入:

<input type="number" name="price" id="price" required>

脚本:

$('#price').on('change', function() {
    var get_price = document.getElementById('price').value;
    var set_price = parseFloat(get_price).toFixed(2);
    $('input[name=price').val(set_price);
})

I had the same requirement but after checking all these answers I realized there is no inbuilt support to block users from typing a particular number of decimal points. step="0.01" is useful when validating the input for a decimal number but still it will not block users from typing any decimal. In my case, I wanted a solution which will prevent user from entering invalid decimal. So I created my own custom JavaScript function which will enforce user any decimal rule. There is a slight performance issue but for my scenario it is okay to have a very small delay to make sure that user is not typing invalid decimal places. It might be useful for someone who wanted to prevent user from typing invalid decimal value on the input.

如果您愿意，可以使用step="0.01"来使用此解决方案。你可以在元素oninput事件上使用下面的函数。如果性能对你来说很重要，那么考虑使用onchange事件而不是oninput。请在data-decimal属性中指定允许输入的最大小数位数。它的值可以从0到任何数字。

function enforceNumberValidation(ele) { if ($(ele).data('decimal') != null) { // found valid rule for decimal var decimal = parseInt($(ele).data('decimal')) || 0; var val = $(ele).val(); if (decimal > 0) { var splitVal = val.split('.'); if (splitVal.length == 2 && splitVal[1].length > decimal) { // user entered invalid input $(ele).val(splitVal[0] + '.' + splitVal[1].substr(0, decimal)); } } else if (decimal == 0) { // do not allow decimal place var splitVal = val.split('.'); if (splitVal.length > 1) { // user entered invalid input $(ele).val(splitVal[0]); // always trim everything after '.' } } } } <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <input type="number" data-decimal="0" oninput="enforceNumberValidation(this)" placeholder="No decimal places" value="" /> <input type="number" data-decimal="2" oninput="enforceNumberValidation(this)" placeholder="2 decimal places" value="" /> <input type="number" data-decimal="5" oninput="enforceNumberValidation(this)" placeholder="5 decimal places" value="" />

我可以使用RegExp来识别无效值，但我还必须恢复输入中的更改。所以我决定不使用RegExp。

使用Javascript在文本框中只输入3个小数点。

<input type="text" class="form-control" onkeypress='return AllowOnlyAmountAndDot(this,event,true);/>

function AllowOnlyAmountAndDot(id, e, decimalbool) {    
    if(decimalbool == true) {   
        var t = id.value;
        var arr = t.split(".");
        var lastVal = arr.pop();
        var arr2 = lastVal.split('');
        if (arr2.length > '2') {
            e.preventDefault();
        } 
    }
}