[英]Fill HTML table with values from JS loop
我希望我的表“分数”由对象中保存的“能力”值填充。
我相信我的问题在于以下几行:
var player = document.getElementById("player" + i + 1);
playerscore.innerText = playerList[i].ability;
我可以通过不使用值“ i”来增加ID来使其工作,我只需为每个ID编写一行代码即可。 我确定这不是最好的处理方式,因此希望使用已设置的循环遍历ID。
我的代码哪里出了问题,哪种更好的方法呢?
提前致谢。
var playerList = [ {name: "player1", highScore: 1, ability: 8}, {name: "player2", highScore: 1, ability: 7}, {name: "player3", highScore: 1, ability: 6}, {name: "player4", highScore: 1, ability: 5}, {name: "player5", highScore: 1, ability: 4}, {name: "player6", highScore: 1, ability: 3}, {name: "player7", highScore: 1, ability: 2}, {name: "player8", highScore: 1, ability: 1} ]; for (var i = 0; i < playerList.length; i++) { console.log(i); var player = document.getElementById("player" + i + 1); var playerscore = document.getElementById('player' + i + 1 + "score") var progress=Math.random(); progress=11*progress; progress=Math.floor(progress); playerList[i].ability=playerList[i].ability+progress; console.log(playerList[i]) //add players score to the table// playerscore.innerText = playerList[i].ability; }
<table> <tr> <th>Player</th> <th>Score</th> </tr> <tr> <td id="player1">1</td> <td id="player1score">0</td> </tr> <tr> <td id="player2">2</td> <td id="player2score">0</td> </tr> <tr> <td id="player3">3</td> <td id="player3score">0</td> </tr> <tr> <td id="player4">4</td> <td id="player4score">0</td> </tr> <tr> <td id="player5">5</td> <td id="player5score">0</td> </tr> <tr> <td id="player6">6</td> <td id="player6score">0</td> </tr> <tr> <td id="player7">7</td> <td id="player7score">0</td> </tr> <tr> <td id="player8">8</td> <td id="player8score">0</td> </tr> </table>
最初的问题是您没有正确取消对计数变量的引用,因此数学计算出了错误的索引以在字符串连接中使用。
要解决此问题,您需要将“ i +1”表达式放入getElementById调用中的一组普通括号中。
基本上是您的首次通话:
var player = document.getElementById("player" + i + 1);
需要成为:
var player = document.getElementById("player" + (i + 1));
在以前的版本中,结果是最后一个1变成一个字符串,并因此成为字符串的一部分,而不是按预期方式添加到索引中。
在vanilla JS中尝试做的更好的方法是首先跳过所有这些+1工作,并使代码可重用。
如果按照W3C建议格式化表格,那么最终将得到如下所示的内容:
<table id="myTable">
<thead>
<tr>
<th>Player</th>
<th>Score</th>
</tr>
</thead>
<tbody id="myTableBody">
<tr>
<td>Player 1</td>
<td>1</td>
</tr>
<tr>
<td>Player 2</td>
<td>2</td>
</tr>
<!-- More TR's here as needed -->
</tbody>
</table>
使用thead和tbody意味着您可以彼此分开操作表的标题和正文部分,从而使您可以使用基础的JS api和表属性,而不必执行构建字符串并可能获取它的冒险步骤字符串格式错误。
我并不是说构建字符串是错误的方法,但是它很容易出错,并且正如您所看到的那样,它只需要一个小的计算错误,最后得到的ID名称与任何内容都不匹配。
在JavaScript的程序控制下向表中添加行很简单,如下所示:
function addRow(playerName, playerScore)
{
var tableBody = document.getElementById('myTableBody');
var newRow = tableBody.insertRow(tableBody.rows.length);
var nameCell = newRow.insertCell(0);
var scoreCell = newRow.insertCell(1);
var playerText = document.createTextNode(playerName);
var scoreText = document.createTextNode(playerScore);
nameCell.appendChild(playerText);
scoreCell.appendChild(scoreText);
}
这样会将新行添加到表主体的末尾。按索引删除行很简单:
function removeRow(rowNumber)
{
var tableBody = document.getElementById('myTableBody');
tableBody.deleteRow(rowNumber);
}
要记住的重要事项是,删除行后,其余的将立即移入该位置。 这意味着,如果删除第一个(行0),则在完成后,1将变为0,2将变为1,3将变为2,依此类推。
这意味着,如果要删除前两个索引,则需要删除两次索引0,而不是您想的那样删除0和1。
至于将数据数组添加到表中,加上add函数,它现在变得非常简单:
playerList.forEach(function(listItem){
addRow(listItem.name, listItem.ability)
});
如果您需要更改实际的文本数据,只需执行以下操作即可:
function changePlayerName(rowNumber, playerName)
{
var tableBody = document.getElementById('myTableBody');
tableBody.Rows[rowNumber].cells[0].innerText = playerName;
}
function changePlayerScore(rowNumber, playerScore)
{
var tableBody = document.getElementById('myTableBody');
tableBody.Rows[rowNumber].cells[1].innerText = playerScore;
}
通过这种方式,可以使您的代码保持整洁,易于阅读和理解。 一个月后再使用它,您仍然可以了解要达到的目标,并且可以帮助您学习。
还有许多其他方法可以完成此操作。 您可以像在原始版本中一样将ID放置在所有标签上,然后通过字符串连接(使用的方法)对其进行引用,可以将带有行ID的类选择器用于实际的直接元素,也可以使用JQuery太。
但是,如果您要为游戏外观构建复杂的UI,那么我强烈建议您考虑使用现代的UI构建系统,例如“ Aurelia”或“ Angular”,两者都使用较新的JS2016 / 2017语法,从而允许您可以编写非常干净的代码,并具有易于理解的结构,例如“ for循环”,“重复循环”以及现代JavaScript带来的所有其他不错的功能。 也不必担心与现代UI框架的向后兼容性,因为它们大多数将构建与旧版浏览器兼容的代码。
尽管我坚信要像在此任务中一样使用香草JavaScript,但我还是相信如果可能的话,使任务更容易。
将您的i + 1
包裹在getElementById
括号中-参见下面的演示:
var playerList = [ {name: "player1", highScore: 1, ability: 8}, {name: "player2", highScore: 1, ability: 7}, {name: "player3", highScore: 1, ability: 6}, {name: "player4", highScore: 1, ability: 5}, {name: "player5", highScore: 1, ability: 4}, {name: "player6", highScore: 1, ability: 3}, {name: "player7", highScore: 1, ability: 2}, {name: "player8", highScore: 1, ability: 1} ]; for (var i = 0; i < playerList.length; i++) { var player = document.getElementById("player" + (i + 1)); var playerscore = document.getElementById('player' + (i + 1) + "score") var progress=Math.random(); progress=11*progress; progress=Math.floor(progress); playerList[i].ability=playerList[i].ability+progress; //add players score to the table// playerscore.innerText = playerList[i].ability; }
<table> <tr> <th>Player</th> <th>Score</th> </tr> <tr> <td id="player1">1</td> <td id="player1score">0</td> </tr> <tr> <td id="player2">2</td> <td id="player2score">0</td> </tr> <tr> <td id="player3">3</td> <td id="player3score">0</td> </tr> <tr> <td id="player4">4</td> <td id="player4score">0</td> </tr> <tr> <td id="player5">5</td> <td id="player5score">0</td> </tr> <tr> <td id="player6">6</td> <td id="player6score">0</td> </tr> <tr> <td id="player7">7</td> <td id="player7score">0</td> </tr> <tr> <td id="player8">8</td> <td id="player8score">0</td> </tr> </table>
var playerList = [ {name: "player1", highScore: 1, ability: 8}, {name: "player2", highScore: 1, ability: 7}, {name: "player3", highScore: 1, ability: 6}, {name: "player4", highScore: 1, ability: 5}, {name: "player5", highScore: 1, ability: 4}, {name: "player6", highScore: 1, ability: 3}, {name: "player7", highScore: 1, ability: 2}, {name: "player8", highScore: 1, ability: 1} ]; for (var i = 0; i < playerList.length; i++) { console.log(i); var player = document.getElementById("player" + (i + 1)); var playerscore = document.getElementById('player' + (i + 1) + "score") var progress=Math.random(); progress=11*progress; progress=Math.floor(progress); playerList[i].ability=playerList[i].ability+progress; console.log(playerList[i]) //add players score to the table// playerscore.innerText = playerList[i].ability; }
<table> <tr> <th>Player</th> <th>Score</th> </tr> <tr> <td id="player1">1</td> <td id="player1score">0</td> </tr> <tr> <td id="player2">2</td> <td id="player2score">0</td> </tr> <tr> <td id="player3">3</td> <td id="player3score">0</td> </tr> <tr> <td id="player4">4</td> <td id="player4score">0</td> </tr> <tr> <td id="player5">5</td> <td id="player5score">0</td> </tr> <tr> <td id="player6">6</td> <td id="player6score">0</td> </tr> <tr> <td id="player7">7</td> <td id="player7score">0</td> </tr> <tr> <td id="player8">8</td> <td id="player8score">0</td> </tr> </table>
您在级联时遇到问题,假设i = 0,那么这个"player" + i + 1 = player01
以便让player1像这样"player" + (i + 1)
。 这将首先计算方括号,然后将其与字符串连接。
“ player” + i + 1的结果将不符合预期。 您可以将i + 1存储在变量中,并在getElementById()中使用它。
var index = i + 1;
var player = document.getElementById("player" + index);
var playerscore = document.getElementById('player' + index + "score")
这是工作中的jsfiddle。
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