javascript - 调整表格大小时如何通过在字符串中间放置省略号来 chop 字符串

Question

我正在尝试在网络上制作文件浏览器的原型(prototype)，它有一个显示文件列表的表格。我想让表格灵活，根据屏幕宽度调整列宽，并 chop 文件名以在单元格中仅显示 1 行文本。我希望它 chop 中间的字符串，而不是尾部的字符串，以显示文件扩展名。

我能够通过一些研究来编写代码。但问题是，代码似乎太重了，所以当我测试它时，它会使 web View 变慢并且有时会崩溃。有没有更简单的方法可以得出相同的结果？

• 当调整屏幕大小时，我调用表格单元格的宽度值，数字永远不会低于某个数字 - 但视觉上宽度小于数字。你能告诉我是什么导致了这个问题吗？

function getvisualLength(target){
    var ruler = document.getElementById("ruler");
    ruler.innerHTML = target;
    return ruler.offsetWidth;
}
function getTrimmedString(targetString, targetWidth){
    var tmp = targetString;
    var tail = targetString.substr(targetString.indexOf('.')-3);
    var truncLength = getvisualLength("...");
    var tailLength = getvisualLength(truncLength);
    
    if (getvisualLength(tmp) > targetWidth){
        while (getvisualLength(tmp) > (targetWidth-(truncLength+tailLength+10))){
            tmp = tmp.substr(0, tmp.length-1);
        }
    }
    
    else{
        return tmp;
    }
    
    return tmp+"..."+tail;
}
window.addEventListener("resize", function(){
    var table = document.getElementById("listTable");
    for (var i = 4; i < table.rows.length; i++){
        var getCellWidth = document.getElementById("listTable").rows[0].cells[2].offsetWidth;
        var str = files[i][0];
        var tmp = getTrimmedString(str, getCellWidth);
        document.getElementById("listTable").rows[i].cells[2].innerHTML = tmp;
    }
});
function addListToTable(target, list){
    var table = document.getElementById(target);
    for (var i=0; i<list.length; i++){
        var rowCount = table.rows.length;
        var row = table.insertRow(rowCount);
        var getIconSource;
        
        row.style.cssText = "height:41px; border-bottom: 1px solid #f4f4f4";
        
        for (var k=0; k<thmbIconList.length; k++){
            if (thmbIconList[k][0] == list[i][2]){
                getIconSource = thmbIconList[k][1];
            }
        }
        row.clickStat = "off";
        row.id = "tableRow";
        var checkbox = row.insertCell(0);
        var type = row.insertCell(1);
        var name = row.insertCell(2);
        var owner = row.insertCell(3);
        var lastmodified = row.insertCell(4);
        var update = row.insertCell(5);
        var size = row.insertCell(6);
        checkbox.innerHTML = "<img src=\"assets/unchecked.png\" style = \"width: 16px; display: table-cell; margin: auto;\">"
        type.innerHTML = "<img src=\""+getIconSource+"\"style = \"width: 20px; display: table-cell; margin: auto;\">"
        name.innerHTML = list[i][0];
        name.style.cssText = "display: block;"
        name.style.cssText = "text-align: left; padding-left: 18px";
        owner.innerHTML = "me";
        owner.style.cssText = "min-width: 72px; text-align: center"
        lastmodified.innerHTML = list[i][1];
        lastmodified.style.cssText = "min-width: 72px; text-overflow:ellipsis; overflow: hidden; white-space: nowrap; text-align: center";
        update.innerHTML = list[i][1];
        update.style.cssText = "min-width: 72px; text-align: center";
        size.innerHTML = list[i][3];
        size.style.cssText = "min-width: 72px;text-align: center";        
    }
}
addListToTable("listTable", folders);
addListToTable("listTable", files);

var folders = [["Documents", "Oct 24 2019", "folder","-"], ["MyFolder_1", "Jan 2 2019", "folder","-"], ["MyFolder_2", "Oct 1 2019", "folder","-"]]
var files = [["description20191025.docx","Oct 25 2019","word", "20MB"], ["description20191025.pptx","Oct 25 2019","ppt", "20MB"], ["description20191025.xlsx","Oct 25 2019","excel", "20MB"], ["nppt_slideBackup.nppt","Oct 25 2019","nppt", "20MB"],["7D65EC6E-4A3882CF.png", "Oct 21 2019", "img", "128MB"], ["photo-153855424537648538.png", "Oct 17 2019", "img", "1.2MB"], ["photo-1538537642458538.png", "Oct 17 2019", "img", "20MB"], ["photo-15385376424548538.png", "Oct 17 2019", "img", "128MB"], ["photo-15385376425248538.png", "Oct 17 2019", "img", "1.2MB"]]

#ruler { visibility: hidden; white-space: nowrap; }
#listTable{
    width: calc(100% - 20px);
    border-collapse: collapse;
}
.listTable_firstRow{
    height: 41px;
    border-bottom: 1px solid #d8d8d8;
}

<table id = "listTable">
    <tr class = "listTable_firstRow">
        <th style = "width: 54px;"><img src="assets/unchecked.png" style = "width: 16px; display: table-cell; margin: auto;" id = "tableSelAll"></th>
        <th style = "width: 54px;">Type</th>
        <th style = "text-align: left;padding-left: 18px; min-width: 0px;">Name</th>
        <th style = "width: 12%; min-width: 72px;">Owner</th>
        <th style = "width: 12%; min-width: 72px;">Last modified</th>
        <th style = "width: 12%; min-width: 72px;">Updated</th>
        <th style = "width: 12%; min-width: 72px;">File size</th>
    </tr>
</table>

Answer 1

您可以使用 JavaScript 的 str.replace(); 函数来实现正则表达式。

可在此处找到示例:Replacing filename with a Regex in JavaScript

您可以拆分每个字符串以删除前三个字符，然后修改示例中的代码以替换文件名中除扩展名之外的所有字符。

像这样:

function truncateFilename(str) {
  // Find first 3 characters of filename
  var start = str.substring(0,3);

  /* Replace everything before the final '.' with an ellipsis.
   * The final '.' is retained and therefore only two additional '.' are needed.
   */
  var end = str.replace(/^.*(?=\.[^.]+$)/g, "..");

  /* Append resulting extention to the first 3 characters of
   * the file name that we found earlier.
   */
  return start + end;
}

var filename = "my_very_long_file_name.exe";
console.log(truncateFilename(filename));

我做了 a fiddle这样您就可以对其进行测试。

关于您的尺子问题，我建议您针对您遇到的每个问题发布一个单独的问题，您更有可能找到解决方案。你的问题已经有了答案here . offsetWidth 包括填充、边框等，而 clientWidth 测量元素的实际宽度。你应该尝试:

function getvisualLength(target){
    var ruler = document.getElementById("ruler");
    ruler.innerHTML = target;
    return ruler.clientWidth;
}