Question

我有一个循环，使用自定义属性<li>生成filesize，现在我想用此类搜索所有<li>并对值求和，但它会返回两个值旁边彼此而不是总结价值观。

var myElements = jQuery(".fileRess");
var sumoffilessize = 0;
for (var i = 0; i < myElements.length; i++) {
    var valueofthis = myElements.eq(i).attr("sizefile");
    var valuetostr = valueofthis.toString();
    var sumoffilessize = (valuetostr + sumoffilessize);
}

alert(sumoffilessize);

HTML：

<div id="fileInfo1">
    <div style="clear:both;padding:5px;" class="fileRess" sizefile="206519" id="fileres_0">
        <input size="1" type="file" class="file" name="attach[]" id="attacher" style="display:none" multiple="" value="undefined">206519 </div>
    <div style="clear:both;padding:5px;" class="fileRess" sizefile="290284" id="fileres_1">
        <input size="1" type="file" class="file" name="attach[]" id="attacher" style="display:none" multiple="" value="undefined">290284 </div>
</div>

<div id="result"></div>

Answer 1

在对其进行求和之前，尝试使用sizefile attribute将您从parseInt(numberString)获得的字符串转换为数字

var myElements = jQuery(".fileRess");
var sumoffilessize = 0;
for (var i = 0; i < myElements.length; i++) {
  sumoffilessize += parseInt(myElements.eq(i).attr("sizefile")
}

alert(sumoffilessize);

如果你不转换它，那么string concatenation将会发生，因为+对于字符串连接和数学加法是常见的。它遇到单个string operand时会进行字符串连接。

DEMO

Answer 2

从DOM读取的值是字符串。如果任何操作数是字符串，+将作为字符串连接运算符。

从DOM读取时，需要将字符串转换为Number，然后对其执行算术运算。

将字符串转换为数字有很多选项。见How do I convert a string into an integer in JavaScript?

＆＃13;

var total = 0;

// Iterate over all the elements having the `fileRess` class
$('.fileRess').each(function () {
    // Get the attribute value from DOM
    // Cast to Number by using unary `+` operator
    // Add to the `total` variable
    total += +$(this).attr('sizefile');
});

$('#result').text('Total: ' + total);

＆＃13;

#result {
  margin: 10px;
  color: green;
  font-weight: bold
}

＆＃13;

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.0.0/jquery.min.js"></script>
<div id="fileInfo1">
    <div style="clear:both;padding:5px;" class="fileRess" sizefile="206519" id="fileres_0">
        <input size="1" type="file" class="file" name="attach[]" id="attacher" style="display:none" multiple="" value="undefined">206519 </div>
    <div style="clear:both;padding:5px;" class="fileRess" sizefile="290284" id="fileres_1">
        <input size="1" type="file" class="file" name="attach[]" id="attacher" style="display:none" multiple="" value="undefined">290284 </div>
</div>

<div id="result"></div>

＆＃13;

var total = 0;

// Iterate over all the elements having the `fileRess` class
$('.fileRess').each(function () {
    // Get the attribute value from DOM
    // Cast to Number by using unary `+` operator
    // Add to the `total` variable
    total += +$(this).attr('sizefile');
});
console.log(total);

Updated Fiddle

Answer 3

您只需要替换

var valuetostr = parseInt(valueofthis.toString());

与

Conversion failed when converting the varchar value '--' to data type int

总结JavaScript中自定义attr循环中的值

3 个答案:

DEMO