使用jQuery更改表格單元格的背景顏色

Question

我有一張有6行和x列的表。 我需要將單元格的背景色更改為數組中包含的顏色。 顏色索引與應繪制的行數匹配。 我有下一個顏色數組：

var arr = ["lightgreen", "orange", "red"];

還有我的jQuery腳本：

$.each(arr, function(index, val) {
$("tr:eq(" + (index) + ")").css("background-color", val);
});

這段代碼僅以不同的顏色繪制了前三行。 我需要這樣的輸出表：

lightgreen lightgreen lightgreen lightgreen
orange orange orange orange
orange orange orange orange
red red red red
red red red red
red red red red

我的jsfiddle： http : //jsfiddle.net/kvdokq13/

Answer 1

您想每次處理N行 ，而使用$("tr:eq(" + (index) + ")")僅選擇唯一的第N行！

您可以這樣實現：

var arr = ["lightgreen", "orange", "red"];
var $rows = $('tr');
var nextRow = 0;
$.each(arr, function(index, val) {
    for (var i = 0; i < index + 1; i++) {
    $rows.eq(nextRow++).css("background-color", val);
  }
});

http://jsfiddle.net/kvdokq13/6/

對於更一般的用途，請注意，應該對其進行增強以適當地照顧到數組長度和行數之間的差異：當前，它假定完全有(1 + 2 + ... + N)行！

Answer 2

修改了Azim的解決方案...

var arr = ["lightgreen", "orange", "red"];
var tr = $('table tr');

for (var i=0; i<tr.length; i++){
  $(tr[i]).css("background-color", arr[i]);
   if (i>2){
        $(tr[i]).css("background-color", arr[2]);
  }    
}

http://jsfiddle.net/kvdokq13/5/

僅使用CSS可以提高效率，但是我猜必須使用JQuery嗎？

Answer 3

您應該保持編號需要跳過多少行：

var arr = ["lightgreen", "orange", "red"];
var skip = 0;
$.each(arr, function(index, val) {
    var _repeat = index+1; // js arrays are zero indexed
    for (var i = 0; i < _repeat; i++) 
        $("tr:eq(" + (i+skip) + ")").css("background-color", val);
  skip = skip + _repeat;
});

更新的小提琴

Answer 4

盡管您已經接受了該問題的答案，但我認為我會使用普通JavaScript而不是庫來替代，以防萬一可能有用。

請注意，盡管我將發布替代方法（在答案的“主要”部分下方）以顯示一個ECMAScript 6功能，“胖箭頭”語法和Array.from() （請參閱下面的參考資料），但我已經使用了它們。如果您還不願意使用ES6，請選擇其他實現）。

也就是說，我自己的解決方法是：

// the colors Array:
var colors = ["lightgreen", "orange", "red"],
// a reference to the <table> element that is
// to be coloured:
  table = document.querySelector('table');

// declaring the relevant function to handle the 
// colouring:
function colorNRows(arr, table) {

  // caching the rows of the table:
  var rows = table.rows,

  // using Array.from() to convert the HTMLCollection
  // into an Array:
    clone = Array.from(rows),

  // iterating over the array of colours, using
  // Array.prototype.map(),
  // row:   the array-element of the array over which
  //        we're iterating,
  // index: the index of the current array-element
  //        in that array,
  // array: (unused here), the array over which we're
  //        iterating.
    segments = arr.map(function(row, index, array) {

      // removing 'index+1' elements of the array from
      // the clone Array, starting at index 0 and
      // returning the removed row(s) to form a new
      // Array:
      return clone.splice(0, index + 1);

    // iterating over the newly-formed Array,
    // using Array.prototype.forEach();
    // the automagically-passed array-elements
    // are, as above, the array-element (of the new
    // array) and the index of the current
    // array-element (in that array):
    }).forEach(function(rowSegments, index) {

      // here we iterate over the array(s) held
      // in each array-element, again using the
      // automagic variables are the same as above
      // relative to the current array.

      // we're using the 'fat arrow' syntax to pass
      // the array-element (toColor) into the
      // the process on the right hand side, thereby
      // styling the backgroundColor of each array-element
      // (a <tr>) according to the color held in the 'arr'
      // array, at the index held in the outer forEach():
      rowSegments.forEach(toColor => toColor.style.backgroundColor = arr[index]);
    });
}

// calling the function:
colorNRows(colors, table);

 var colors = ["lightgreen", "orange", "red"], table = document.querySelector('table'); function colorNRows(arr, table) { var rows = table.rows, clone = Array.from(rows), segments = arr.map(function(row, index, array) { return clone.splice(0, index + 1); }).forEach(function(rowSegments, index) { rowSegments.forEach(toColor => toColor.style.backgroundColor = arr[index]); }); } colorNRows(colors, table); 

 <table border="4" cellpadding="4" cellspacing="4"> <tr> <td>1</td> <td>2</td> <td>3</td> <td>4</td> <td>5</td> <td>6</td> <td>7</td> <td>8</td> <td>9</td> <td>10</td> </tr> <tr> <td>11</td> <td>12</td> <td>13</td> <td>14</td> <td>15</td> <td>16</td> <td>17</td> <td>18</td> <td>19</td> <td>20</td> </tr> <tr> <td>21</td> <td>22</td> <td>23</td> <td>24</td> <td>25</td> <td>26</td> <td>27</td> <td>28</td> <td>29</td> <td>30</td> </tr> <tr> <td>31</td> <td>32</td> <td>33</td> <td>34</td> <td>35</td> <td>36</td> <td>37</td> <td>38</td> <td>39</td> <td>40</td> </tr> <tr> <td>41</td> <td>42</td> <td>43</td> <td>44</td> <td>45</td> <td>46</td> <td>47</td> <td>48</td> <td>49</td> <td>50</td> </tr> <tr> <td>51</td> <td>52</td> <td>53</td> <td>54</td> <td>55</td> <td>56</td> <td>57</td> <td>58</td> <td>59</td> <td>60</td> </tr> </table> 

JS小提琴演示 。

刪除ES6功能以與大多數現代瀏覽器兼容，這給我們留下了以下內容（所有內容都與注釋的代碼完全相同）：

function colorNRows(arr, table) {
  var rows = table.rows,

  // cloning the rows HTMLCollection, using
  // Array.prototype.slice() in conjunction with
  // Function.prototype.call(), to allow us to use
  // slice() on the Array-like collection:
    clone = Array.prototype.slice.call(rows, 0),

    segments = arr.map(function(row, index, array) {
      return clone.splice(0, index + 1);
    }).forEach(function(rowSegments, index) {

      // here, rather than a fat arrow function,
      // we explicitly use an inner forEach() loop
      // performing the same action, but slightly
      // more verbose:
      rowSegments.forEach(function(toColor) {
        toColor.style.backgroundColor = arr[index];
      })
    });
}

 var colors = ["lightgreen", "orange", "red"], table = document.querySelector('table'); function colorNRows(arr, table) { var rows = table.rows, clone = Array.prototype.slice.call(rows, 0), segments = arr.map(function(row, index, array) { return clone.splice(0, index + 1); }).forEach(function(rowSegments, index) { rowSegments.forEach(function(toColor) { toColor.style.backgroundColor = arr[index]; }) }); } colorNRows(colors, table); 

 <table border="4" cellpadding="4" cellspacing="4"> <tr> <td>1</td> <td>2</td> <td>3</td> <td>4</td> <td>5</td> <td>6</td> <td>7</td> <td>8</td> <td>9</td> <td>10</td> </tr> <tr> <td>11</td> <td>12</td> <td>13</td> <td>14</td> <td>15</td> <td>16</td> <td>17</td> <td>18</td> <td>19</td> <td>20</td> </tr> <tr> <td>21</td> <td>22</td> <td>23</td> <td>24</td> <td>25</td> <td>26</td> <td>27</td> <td>28</td> <td>29</td> <td>30</td> </tr> <tr> <td>31</td> <td>32</td> <td>33</td> <td>34</td> <td>35</td> <td>36</td> <td>37</td> <td>38</td> <td>39</td> <td>40</td> </tr> <tr> <td>41</td> <td>42</td> <td>43</td> <td>44</td> <td>45</td> <td>46</td> <td>47</td> <td>48</td> <td>49</td> <td>50</td> </tr> <tr> <td>51</td> <td>52</td> <td>53</td> <td>54</td> <td>55</td> <td>56</td> <td>57</td> <td>58</td> <td>59</td> <td>60</td> </tr> </table> 

JS小提琴演示 。

參考文獻：

• Array.from() 。
• 箭頭（“胖箭頭”）功能： => 。
• Array.prototype.forEach() 。
• Array.prototype.map() 。
• Array.prototype.slice() 。
• Array.prototype.splice() 。
• document.querySelector() 。
• Function.prototype.call() 。
• HTMLTableElement 。
• HTMLTableElement.rows 。