javascript - jQuery:查找并计算包含变量的元素

Question

我在表中有一长串行 (tr)。

我想找到第三个 td 中每次出现的“M”，所以我想出了这个:

$(document).ready(function() {

    function countInstance(needle) {
        var count = 0;
        $("table").find("TR TD:nth-child(3):contains(' "+needle+" ')").each(function() {
            count += 1;
        });
        console.log(count);
    };

    countInstance("M");

});

但是控制台不会返回修改后的计数。理想情况下，我还想搜索和计算其他 td 元素中其他变量的出现次数，将每个变量记录到变量或将它们推送到数组。

编辑:

大部分已解决，但这似乎有点不准确。

$(document).ready(function() {

    function countInstance(tdNum, needle) {
        var count = 0;
        $('table TR').find('TD:nth-child(' +tdNum+ '):contains(' +needle+ ')').each(function() {
            count += 1;
        });
        console.log(count);
    };

    countInstance(3, 'M');

});

Answer 1

function countInstance(tdNum, needle) {
	var contents = $("table tr").find("td:nth-child(" + tdNum + ")").text();
	count = contents.split(needle).length - 1;
	console.log(count);
};

var result1 = countInstance(3, "M");

function countInstance2(tdNum, needle) {
	var count = 0;
    $('table TR').find('TD:nth-child(' +tdNum+ '):contains(' +needle+ ')').each(function() {
		count += 1;
	});
    console.log(count);
};

var result2 = countInstance2(3,"M");

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<table>
    <tr>
        <td>MMMMMMMMM</td>
        <td>MMMMMMMM</td>
        <td>MMMMMMM</td>
    </tr>
</table>

<div id="one"></div>
<div id="two"></div>

$(document).ready(function() {

    function countInstance(tdNum, needle) {
        var contents = $("table tr").find("td:nth-child(" + tdNum + ")").text();
        count = contents.split(needle).length - 1;
        console.log(count);
    };

    countInstance(3, "M");

});