Question

使用下面的html和Javascript我计算在输入字段中输入的字符数，并将它们限制为30.我还向用户显示一个计数器。

此计数器会更改此事件的值：onfocus，onKeyDown，onKeyUp，onpaste。

我无法让onpaste工作。当用户使用“CTRL V”粘贴时，计数器会更改值，但使用鼠标/右键单击粘贴时，计数器不会更改。我做错了什么？

Jsfiddle： https://jsfiddle.net/ow3ubgp0/

HTML：

<input readonly type="text" name="countdown1" size="5" value="30" />

<input type="text" id="my_text_input" name="my_text_input" onfocus="limitText(this.form.my_text_input,this.form.countdown1,30);" onKeyDown="limitText(this.form.my_text_input,this.form.countdown1,30);" onKeyUp="limitText(this.form.my_text_input,this.form.countdown1,30);" onpaste="limitText(this.form.my_text_input,this.form.countdown1,30);" />

使用Javascript：

function limitText(limitField, limitCount, limitNum) {
    if (limitField.value.length > limitNum) {
        limitField.value = limitField.value.substring(0, limitNum);
    } else {
        limitCount.value = limitNum - limitField.value.length;
    }
}

Answer 1

你好用下面的代码检查

我希望它有所帮助

<html>
<form>
<input readonly type="text" name="countdown1" size="5" value="30" />

<input type="text" id="my_text_input" name="my_text_input" onfocus="limitText(this.form.my_text_input,this.form.countdown1,30);" onKeyDown="limitText(this.form.my_text_input,this.form.countdown1,30);" onKeyUp="limitText(this.form.my_text_input,this.form.countdown1,30);" onpaste="limitText(this.form.my_text_input,this.form.countdown1,30);" onChange="limitText(this.form.my_text_input,this.form.countdown1,30);" oninput="limitText(this.form.my_text_input,this.form.countdown1,30);"/>
</form>
<script>
function limitText(limitField, limitCount, limitNum) {
    if (limitField.value.length > limitNum) {
        limitField.value = limitField.value.substring(0, limitNum);
    } else {
        limitCount.value = limitNum - limitField.value.length;
    }
}
</script>
</html>

Answer 2

这是一个有效的fiddle。

oninput：当用户在某个字段中写入内容时执行JavaScript。

<form>
        <input readonly type="text" name="countdown1" size="5" value="30" />

        <input onfocus="limitText(this.form.my_text_input,this.form.countdown1,30);" onKeyDown="limitText(this.form.my_text_input,this.form.countdown1,30);" onKeyUp="limitText(this.form.my_text_input,this.form.countdown1,30);" onpaste="limitText(this.form.my_text_input,this.form.countdown1,30);"
    oninput="limitText(this.form.my_text_input,this.form.countdown1,30);" type="text" id="my_text_input" name="my_text_input" /></input>
    </form>

Answer 3

function limitText（limitField，limitCount，limitNum）{if（limitField.value.length＆gt; limitNum）{limitField.value = limitField.value.substring（0，limitNum）; } else {limitCount.value = limitNum - limitField.value.length; }

limitField.value.length为零。它是粘贴的先前值的值。

所以它永远不到limitNum。

Javascript onpaste无法正常工作

3 个答案:

function limitText（limitField，limitCount，limitNum）{if（limitField.value.length＆gt; limitNum）{limitField.value = limitField.value.substring（0，limitNum）; } else {limitCount.value = limitNum - limitField.value.length; }