javascript - 达到 maxlength 值后关注下一个输入

Question

一旦前一个输入达到其最大长度值，我如何聚焦下一个输入？

a: <input type="text" maxlength="5" />
b: <input type="text" maxlength="5" />
c: <input type="text" maxlength="5" />

如果用户粘贴的文本大于最大长度，理想情况下它应该溢出到下一个输入中。

jsfiddle：http: //jsfiddle.net/4m5fg/1/

我必须强调我不想使用插件，因为我更愿意学习这背后的逻辑，而不是使用已经存在的东西。感谢您的理解。

Answer 1

没有使用 jQuery，并且是一个非常干净的实现：

• 从 maxlength 属性读取。
• 扩展到容器内的任意数量的输入。
• 自动查找下一个要关注的输入。
• 没有 jQuery。

http://jsfiddle.net/4m5fg/5/

<div class="container">
a: <input type="text" maxlength="5" />
b: <input type="text" maxlength="5" />
c: <input type="text" maxlength="5" />
</div>

..

var container = document.getElementsByClassName("container")[0];
container.onkeyup = function(e) {
    var target = e.srcElement || e.target;
    var maxLength = parseInt(target.attributes["maxlength"].value, 10);
    var myLength = target.value.length;
    if (myLength >= maxLength) {
        var next = target;
        while (next = next.nextElementSibling) {
            if (next == null)
                break;
            if (next.tagName.toLowerCase() === "input") {
                next.focus();
                break;
            }
        }
    }
    // Move to previous field if empty (user pressed backspace)
    else if (myLength === 0) {
        var previous = target;
        while (previous = previous.previousElementSibling) {
            if (previous == null)
                break;
            if (previous.tagName.toLowerCase() === "input") {
                previous.focus();
                break;
            }
        }
    }
}

Answer 2

您可以观察字段中的输入并测试其值：

$("input").bind("input", function() {
    var $this = $(this);
    setTimeout(function() {
        if ( $this.val().length >= parseInt($this.attr("maxlength"),10) )
            $this.next("input").focus();
    },0);
});

工作演示。

那里是为了setTimeout确保代码只会在输入完成和值更新后运行。绑定input确保大多数类型的输入都会触发事件，包括按键、复制/粘贴（甚至从鼠标）和拖放（尽管在这种情况下，后者不起作用，因为焦点在可拖动对象上，而不是可丢弃）。

注意：在某些较旧的浏览器上，您可能还需要绑定propertychange.

---

如果用户粘贴的文本大于最大长度，理想情况下它应该溢出到下一个输入中。

为此，您可能需要maxlength使用 JavaScript 删除该属性（以便能够捕获完整的输入），并自己实现该功能。我做了一个小例子，相关部分如下：

$("input").each(function() {
    var $this = $(this);
    $(this).data("maxlength", $this.prop("maxlength"));
    $(this).removeAttr("maxlength");
})

这将删除该属性，但将其保存在 中data，以便您以后可以访问它。

function spill($this, val) {
    var maxlength = $this.data("maxlength");
    if ( val.length >= maxlength ) {
        $this.val(val.substring(0, maxlength));
        var next = $this.next("input").focus();
        spill(next, val.substring(maxlength));
    }
    else
        $this.val(val);
}

这里在 JavaScript 中重新引入了最大长度逻辑，以及获取“丢弃”部分并在递归调用中使用它spill。如果没有下一个元素，则调用data将返回undefined并且循环将停止，因此输入将在最后一个字段中被截断。

Answer 3

您可以使用纯 JavaScript：

见演示。

用 . 检查字符长度el.value.length。如果等于最大值，则使用 移动到下一个字段focus()。将此函数绑定到 keyup 事件，onkeyup以便每次用户键入字符后都会触发该函数。

var a = document.getElementById("a"),
    b = document.getElementById("b"),
    c = document.getElementById("c");

a.onkeyup = function() {
    if (this.value.length === parseInt(this.attributes["maxlength"].value)) {
        b.focus();
    }
}

b.onkeyup = function() {
    if (this.value.length === parseInt(this.attributes["maxlength"].value)) {
        c.focus();
    }
}

Answer 4

如果你有很多领域，你可以做这样的事情。

基本上是keyup获取输入的长度，然后将其与最大长度进行比较，如果匹配，则focus到下一个输入字段。

http://jsfiddle.net/btevfik/DVxDA/

$(document).ready(function(){
    $('input').keyup(function(){
        if(this.value.length==$(this).attr("maxlength")){
            $(this).next().focus();
        }
    });
});

Answer 5

let otp = document.querySelector('#otp-screen');

for(let pin of otp.children) {
    pin.onkeyup = function() {
        if(pin.nextElementSibling) {
            pin.nextElementSibling.focus();
        }
    }
}

<div class="otp-screen" id="otp-screen">
    <input type="text" placeholder="0" maxlength="1"/> 
    <input type="text" placeholder="0" maxlength="1"/> 
    <input type="text" placeholder="0" maxlength="1"/> 
    <input type="text" placeholder="0" maxlength="1"/> 
</div>

Answer 6

更新的 btevfik代码，Onkeyup 或 onkeydown 将产生问题，因为您将无法删除选项卡导航上的先前输入。编辑或更改输入框中的文本将很困难，因为它将被限制为最大长度。所以我们可以使用oninput事件来完成任务。

演示

HTML

<ul>
<li>a: <input type="text" maxlength="5" /></li>
<li>b: <input type="text" maxlength="3" /></li>
<li>c: <input type="text" maxlength="5" /></li>
<li>d: <input type="text" maxlength="3" /></li>
<li>e: <input type="text" maxlength="6" /></li>
<li>f: <input type="text" maxlength="10" /></li>
<li>g: <input type="text" maxlength="7" /></li>
</ul>

Javascript

$(document).ready(function(){
    $('input').on("input", function(){
        if($(this).val().length==$(this).attr("maxlength")){
            $(this).next().focus();
        }
    });
});

CSS

ul {list-style-type:none;}
li {padding:5px 5px;}

Answer 7

其他答案确实给出了一些如何实现的想法，但我发现他们没有考虑一些小问题，其中包括：

1. 事实上，您不想在整个页面上自动聚焦任何元素，而是在特定表单内。
2. 输入元素可以包装在其他一些元素中（例如，我将它们包装在span或div允许通过 CSS 浮动标签，并且我已经看到table用于结构的表单）。
3. 字段的有效性，当溢出或自动移动到下一个时。
4. 溢出时的输入事件。
5. 返回前一个字段时的光标位置（看起来可以通过浏览器保存，因此退格可以不在字段的末尾，而是例如在中间）。

下面的代码至少试图解释所有这些。其中大部分都可以在codepen上进行测试：paste-spilling 在那里不起作用，看起来是因为 Clipboard API（其他带有它的 codepen 也不适合我）。
如果代码中有任何不清楚的地方，请告诉我，我会更新我的答案和代码。如果您发现一些未涵盖的边缘案例 - 也请告诉我。

对于使用来自 codepen 的表单进行粘贴溢出测试，您可以使用以下内容：123456789123456789012345678903454353434534

关于它如何在youtube上更“生动”的环境中工作的视频示例

//List of input types, that are "textual" by default, thus can be tracked through keypress and paste events. In essence,
// these are types, that support maxlength attribute
const textInputTypes = ['email', 'password', 'search', 'tel', 'text', 'url', ];

formInit();

//Add listeners
function formInit()
{
    document.querySelectorAll('form input').forEach((item)=>{
        if (textInputTypes.includes(item.type)) {
            //Somehow backspace can be tracked only on keydown, not keypress
            item.addEventListener('keydown', inputBackSpace);
            if (item.getAttribute('maxlength')) {
                item.addEventListener('input', autoNext);
                item.addEventListener('change', autoNext);
                item.addEventListener('paste', pasteSplit);
            }
        }
    });
}


//Track backspace and focus previous input field, if input is empty, when it's pressed
function inputBackSpace(event)
{
    let current = event.target;
    if ((event.keyCode || event.charCode || 0) === 8 && !current.value) {
        let moveTo = nextInput(current, true);
        if (moveTo) {
            moveTo.focus();
            //Ensure, that cursor ends up at the end of the previous field
            moveTo.selectionStart = moveTo.selectionEnd = moveTo.value.length;
        }
    }
}

//Focus next field, if current is filled to the brim and valid
function autoNext(event)
{
    let current = event.target;
    //Get length attribute
    let maxLength = parseInt(current.getAttribute('maxlength'));
    //Check it against value length
    if (maxLength && current.value.length === maxLength && current.validity.valid) {
        let moveTo = nextInput(current, false);
        if (moveTo) {
            moveTo.focus();
        }
    }
}

async function pasteSplit(event)
{
    let permission = await navigator.permissions.query({ name: 'clipboard-read',});
    //Check permission is granted or not
    if (permission.state === 'denied') {
        //It's explicitly denied, thus cancelling action
        return false;
    }
    //Get buffer
    navigator.clipboard.readText().then(result => {
        let buffer = result.toString();
        //Get initial element
        let current = event.target;
        //Get initial length attribute
        let maxLength = parseInt(current.getAttribute('maxlength'));
        //Loop while the buffer is too large
        while (current && maxLength && buffer.length > maxLength) {
            //Ensure input value is updated
            current.value = buffer.substring(0, maxLength);
            //Trigger input event to bubble any bound events
            current.dispatchEvent(new Event('input', {
                bubbles: true,
                cancelable: true,
            }));
            //Do not spill over if a field is invalid
            if (!current.validity.valid) {
                return false;
            }
            //Update buffer value (not the buffer itself)
            buffer = buffer.substring(maxLength);
            //Get next node
            current = nextInput(current);
            if (current) {
                //Focus to provide visual identification of a switch
                current.focus();
                //Update maxLength
                maxLength = parseInt(current.getAttribute('maxlength'));
            }
        }
        //Check if we still have a valid node
        if (current) {
            //Dump everything we can from leftovers
            current.value = buffer;
            //Trigger input event to bubble any bound events
            current.dispatchEvent(new Event('input', {
                bubbles: true,
                cancelable: true,
            }));
        }
    }).catch(err => {
        //Most likely user denied request. Check status
        navigator.permissions.query({ name: 'clipboard-read',}).then(newPerm => {
            if (newPerm.state === 'granted') {
                console.log('Failed to read clipboard', err);
            } else {
                console.log('Request denied by user. Show him some notification to explain why enabling permission may be useful');
            }
        }).catch(errPerm => {
            console.log('Failed to read clipboard', errPerm);
        });
    });
}

//Find next/previous input
function nextInput(initial, reverse = false)
{
    //Get form
    let form = initial.form;
    //Iterate inputs inside the form. Not using previousElementSibling, because next/previous input may not be a sibling on the same level
    if (form) {
        let previous;
        for (let moveTo of form.querySelectorAll('input')) {
            if (reverse) {
                //Check if current element in loop is the initial one, meaning
                if (moveTo === initial) {
                    //If previous is not empty - share it. Otherwise - false, since initial input is first in the form
                    if (previous) {
                        return previous;
                    } else {
                        return false;
                    }
                }
            } else {
                //If we are moving forward and initial node is the previous one
                if (previous === initial) {
                    return moveTo;
                }
            }
            //Update previous input
            previous = moveTo;
        }
    }
    return false;
}

Answer 8

已验证的答案有一个问题，如果前一个字段具有有效长度，则该问题会聚焦前一个字段

我已修改上述答案以修复前一个标签的完整长度

var container = document.getElementsByClassName("container")[0];
    container.onkeyup = function(e) {
    var target = e.srcElement || e.target;
    var maxLength = parseInt(target.attributes["maxlength"].value, 10);
    var myLength = target.value.length;
    if (myLength >= maxLength) {
        var next = target;
        while (next = next.nextElementSibling) {
            if (next == null)
                break;
            if (next.tagName.toLowerCase() === "input") {
                next.focus();
                break;
            }
        }
    }
    // Move to previous field if empty (user pressed backspace)
    else if (myLength === 0) {
         var previous = target;
       // Move to previous field if backspace is pressed
        if (code == 8) {
            previous = previous.previousElementSibling;
            if (previous != null) {
                if (previous.tagName.toLowerCase() === "input") {
                    previous.focus();
                }
            }
        } else {
            while (previous = previous.previousElementSibling) {
                if (previous == null)
                    break;
                if (previous.tagName.toLowerCase() === "input") {
                    var mLength = parseInt(previous.attributes["maxlength"].value, 10);
                    var pMyLength = previous.value.length;
                    // Move to previous field if it does not have required length
                    if (mLength == pMyLength) {
                        break;
                    } else {
                        previous.focus();
                        break;
                    }
                }
            }
        }
    }
}

Answer 9

如果您专注于创建卡（借记卡/信用卡）号码输入类型。然后清理一个易于管理的 jQuery 版本，如下所示：

/*..............................................................................................
* jQuery function for Credit card number input group
......................................................................................................*/
            // make container label of input groups, responsible
            $('.card-box').on('focus', function(e){
                $(this).parent().addClass('focus-form-control');
            });
            $('.card-box').on('blur', function(e){
                $(this).parent().removeClass('focus-form-control');
            });
            $('.card-box-1').on('keyup', function(e){
                e.preventDefault();
                var max_length = parseInt($(this).attr('maxLength'));
                var _length = parseInt($(this).val().length);
                if(_length >= max_length) {
                    $('.card-box-2').focus().removeAttr('readonly');
                    $(this).attr('readonly', 'readonly');
                }
                if(_length <= 0){
                    return;
                }
            });
            $('.card-box-2').on('keyup', function(e){
                e.preventDefault();
                var max_length = parseInt($(this).attr('maxLength'));
                var _length = parseInt($(this).val().length);
                if(_length >= max_length) {
                    $('.card-box-3').focus().removeAttr('readonly');
                    $(this).attr('readonly', 'readonly');
                }
                if(_length <= 0){
                    $('.card-box-1').focus().removeAttr('readonly');
                    $(this).attr('readonly', 'readonly');
                }
            });
             $('.card-box-3').on('keyup', function(e){
                e.preventDefault();
                var max_length = parseInt($(this).attr('maxLength'));
                var _length = parseInt($(this).val().length);
                if(_length >= max_length) {
                    $('.card-box-4').focus().removeAttr('readonly');
                    $(this).attr('readonly', 'readonly');
                }
                if(_length <= 0){
                    $('.card-box-2').focus().removeAttr('readonly');
                    $(this).attr('readonly', 'readonly');
                }
            });
            $('.card-box-4').on('keyup', function(e){
                e.preventDefault();
                var max_length = parseInt($(this).attr('maxLength'));
                var _length = parseInt($(this).val().length);
                if(_length >= max_length) {
                    return;
                }
                if(_length <= 0){
                    $('.card-box-3').focus().removeAttr('readonly');
                    $(this).attr('readonly', 'readonly');
                }
            });
/*..............................................................................................
* End jQuery function for Credit card number input group
......................................................................................................*/

/* Hide HTML5 Up and Down arrows. */
                                input[type="number"]::-webkit-outer-spin-button, input[type="number"]::-webkit-inner-spin-button {
                                    -webkit-appearance: none; margin: 0;
                                }
                                input[type="number"] { -moz-appearance: textfield; }
                                .card-box {
                                    width: 20%; display: inline-block; height: 100%; border: none;
                                }
                                
                                .focus-form-control {
                                    border-color: #66afe9; outline: 0;-webkit-box-shadow: inset 0 1px 1px rgba(0,0,0,.075), 0 0 8px rgba(102, 175, 233, .6);
                                        box-shadow: inset 0 1px 1px rgba(0,0,0,.075), 0 0 8px rgba(102, 175, 233, .6);
                                }

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.0/jquery.min.js"></script>
<div class="form-control" style="padding: 0; max-width: 300px; ">
                                        <input class="card-box card-box-1" type="number" id="CreditCard_CardNumber1" required step="1" minlength="4" maxlength="4" pattern="[0-9]{4}" value="" placeholder="0000"
                                            onClick="this.setSelectionRange(0, this.value.length)" oninput="this.value=this.value.slice(0,this.maxLength||'');this.value=(this.value < 1) ? ('') : this.value;"/> 
                                        <input class="card-box card-box-2" type="number" id="CreditCard_CardNumber2" readonly required step="1" minlength="4" maxlength="4" pattern="[0-9]{4}" value="" placeholder="0000"
                                            onClick="this.setSelectionRange(0, this.value.length)" oninput="this.value=this.value.slice(0,this.maxLength||'');this.value=(this.value < 1) ? ('') : this.value;" />
                                        <input class="card-box card-box-3" type="number" id="CreditCard_CardNumber3" readonly required step="1" minlength="4" maxlength="4" pattern="[0-9]{4}" value="" placeholder="0000"
                                            onClick="this.setSelectionRange(0, this.value.length)" oninput="this.value=this.value.slice(0,this.maxLength||'');this.value=(this.value < 1) ? ('') : this.value;" />
                                        <input class="card-box card-box-4" type="number" id="CreditCard_CardNumber4" readonly required step="1" minlength="4" maxlength="4" pattern="[0-9]{4}" value="" placeholder="0000"
                                            onClick="this.setSelectionRange(0, this.value.length)" oninput="this.value=this.value.slice(0,this.maxLength||'');this.value=(this.value < 1) ? ('') : this.value;" />
                                    </div>

Answer 10

如果您要动态添加输入文本字段，那么您可以试试这个。

这会将脚本重新注入 DOM 并完美运行。

$('body').on('keyup', '#num_1',function(){
  if (this.value.length === parseInt(this.attributes["maxlength"].value)) {
    $('#num_2').focus();
  }
})
$('body').on('keyup','#num_2', function(){
   if (this.value.length === parseInt(this.attributes["maxlength"].value)) {
    $('#num_3').focus();
  }
})

<input type="text" class="form-control" name="number" maxlength="3" id="num_1">
<input type="text" class="form-control" name="number" maxlength="3" id="num_2">
<input type="text" class="form-control" name="number" maxlength="4" id="num_3">