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首页 > 解决方案 > 我添加了三个输入数字的最大值并且它有效但是如何添加递增递减按钮而不丢失最大值？

javascript - 我添加了三个输入数字的最大值并且它有效但是如何添加递增递减按钮而不丢失最大值？

问题描述

我需要添加一个三元素是8，点击+和-按钮。但是，我不希望它将每个元素增加到 8 个。 

// Addtion of select items LINK - https://stackoverflow.com/questions/49644837/set-max-value-of-three-input-numbers-together
var max = 8;
var $inputs = $('input');

function sumInputs($inputs) {
    var sum = 0;

    $inputs.each(function() {
        sum += parseInt($(this).val(), 0);
    });

    return sum;
}

$inputs.on('input', function(e) {
    var $this = $(this);
    var sum = sumInputs($inputs.not(function(i, el) {
        return el === e.target;
    }));
    var value = parseInt($this.val(), 10) || 0;
    if (sum + value > max) $this.val(max - sum);
});


//Increment Decrement value

function up(max) {
    document.getElementById("myNumber").value = parseInt(document.getElementById("myNumber").value) + 1;

    if (document.getElementById("myNumber").value >= parseInt(max)) {
        document.getElementById("myNumber").value = max;

    }
}

function down(min) {
    document.getElementById("myNumber").value = parseInt(document.getElementById("myNumber").value) - 1;
    if (document.getElementById("myNumber").value <= parseInt(min)) {
        document.getElementById("myNumber").value = min;
    }
}


function up2(max) {
    document.getElementById("myNumber2").value = parseInt(document.getElementById("myNumber2").value) + 1;
    if (document.getElementById("myNumber2").value >= parseInt(max)) {
        document.getElementById("myNumber2").value = max;
    }
}

function down2(min) {
    document.getElementById("myNumber2").value = parseInt(document.getElementById("myNumber2").value) - 1;
    if (document.getElementById("myNumber2").value <= parseInt(min)) {
        document.getElementById("myNumber2").value = min;
    }
}


function up3(max) {
    document.getElementById("myNumber3").value = parseInt(document.getElementById("myNumber3").value) + 1;
    if (document.getElementById("myNumber3").value >= parseInt(max)) {
        document.getElementById("myNumber3").value = max;
    }
}

function down3(min) {
    document.getElementById("myNumber3").value = parseInt(document.getElementById("myNumber3").value) - 1;
    if (document.getElementById("myNumber3").value <= parseInt(min)) {
        document.getElementById("myNumber3").value = min;
    }
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
<div class="select-1">
    <button type="submit" value="-" onclick=" down('0')" class="sub" id="">-</button>
    <input type="number" id="myNumber" value="0" name="qty" max="8" min="0" step="1"/>
    <button type="submit" value="+" onclick="up('8')" class="add">+</button>
</div>
<div class="select-2">
    <button type="submit" value="-" onclick=" down2('0')" class="sub">-</button>
    <input type="number" id="myNumber2" value="0" name="qty2" max="8" min="0" step="1"/>
    <button type="submit" value="+" onclick="up2('8')" class="add">+</button>
</div>
<div class="select-3">
    <button type="submit" value="-" onclick=" down3('0')" class="sub" id="">-</button>
    <input type="number" id="myNumber3" value="0" name="qty3" max="8" min="0" step="1"/>
    <button type="submit" value="+" onclick="up3('8')" class="add">+</button>
</div>

目前，最大值是 8。我也想用 + 和 - 按钮获得最大值。

如何使用 javascript 或 jquery 解决这个问题？

在这里，我在下面有一个链接，用于递增和递减。 https://stackoverflow.com/a/49645518/15412266

标签： javascripthtmljquery

解决方案

<!DOCTYPE html>
<html>
<head>
    <title></title>
</head>
<body>
    <div>
        

        <button type="submit" value="+" onclick="minusoperation(1)" class="minus">-</button>
        <input type="number" class="numbers" id="number1" min="0" max="8" onchange="inputNumber(this)" data-prevvalue=0 />
        <button type="submit" value="+" onclick="plusoperation(1)" class="plus">+</button>

        <button type="submit" value="+" onclick="minusoperation(2)" class="minus">-</button>
        <input type="number" class="numbers" id="number2" min="0" max="8" onchange="inputNumber(this)" data-prevvalue=0 />
        <button type="submit" value="+" onclick="plusoperation(2)" class="plus">+</button>


        <button type="submit" value="+" onclick="minusoperation(3)" class="minus">-</button>
        <input type="number" class="numbers" id="number3" min="0" max="8" onchange="inputNumber(this)" data-prevvalue=0 />
        <button type="submit" value="+" onclick="plusoperation(3)" class="plus">+</button>


    </div>

    <script type="text/javascript">
        function inputNumber(el)
        {
            
            var myElements = document.getElementsByClassName('numbers');
            var sum = 0;
            for (var i=0;i<myElements.length;i++) {
                if(myElements[i].value)
                    sum = sum+parseInt(myElements[i].value);
            }
            if(sum<=8)
            {
                el.dataset.prevvalue  = el.value;
            } else {
                el.value  = el.dataset.prevvalue;
            }

        }

        function minusoperation(inputNumber)
        {

            var el = document.getElementById('number'+inputNumber);
            if(parseInt(el.value))
            {
                el.value = parseInt(el.value)-1;

            } else {
                el.value = 0;
            }
            el.onchange();
        }

        function plusoperation(inputNumber)
        {
            var el = document.getElementById('number'+inputNumber);

            if(parseInt(el.value))
            {
                el.value = parseInt(el.value)+1;
            } else {
                el.value = 1;
            }
            el.onchange();

        }

    </script>
</body>
</html>

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