Question

我一直在努力想要解决这个问题。为什么在多行文本框asp控件中，我有140个字符的限制，但有时我可以输入141或142个字符，特别是使用回车键？

这是我的代码

function CheckSize(o, size) {
    if (o != null) {
        var s = o.value.length;
        if (s > size) {
            debugger;
            alert('Lamentamos mas foi atingido o limite máximo para o texto a introduzir.\nSugerimos que introduza um texto com menos de ' + size + ' caracteres.\nAgradecemos a sua compreensão.');
            // alert(resources.error_reachedMaxNumberOfChars.replace("{0}",String(size)));
            var trim = o.value.trim();
            o.value = trim.substring(0, size - 1);
        }
    }
}

Answer 1

请尝试以下代码：

function CheckSize(textBox, maxLength)
{
    if (textBox.value.length > maxLength)
    {
        alert("Max characters allowed are " + maxLength);
        textBox.value = textBox.value.substr(0, maxLength);
    }
}

Answer 2

我的猜测是，您是否遇到了许多现代浏览器中出现的相当常见的maxLength错误（do a Google search about it）。这是您可以解决的一个示例问题，虽然没有为每种情况（即粘贴）硬化。

CSS

.hidden {
    visibility: hidden;
}

HTML

<textarea id="myTextbox" maxlength="140" rows="4" cols="35"></textarea>
<div id="count">0</div>
<div id="alert" class="hidden">At max chars!</div>
<div id="newline" class="hidden">Newline prevented as it is 2 characters!</div>

的Javascript

var myTextBox = document.getElementById('myTextbox'),
    count = document.getElementById('count'),
    alert = document.getElementById('alert'),
    newline = document.getElementById('newline'),
    maxLength = 140;

myTextBox.addEventListener('input', function (e) {
    var value = e.target.value.replace(/\r?\n/g, '\r\n'),
        length = value.length;


    if (length >= maxLength) {
        if (length > maxLength) {
            length = maxLength - 1;
            e.target.value = value.slice(0, length);
            newline.classList.remove('hidden');
        } else {
            alert.classList.remove('hidden');
            newline.classList.add('hidden');
        }
    } else {
        alert.classList.add('hidden');
        newline.classList.add('hidden');
    }

    count.textContent = length;
}, false);

在jsFiddle

上

检查多行文本框的大小

2 个答案: