此选择器为什么起作用:
document.querySelectorAll('table tr:not(:nth-child(even))');
虽然此选择器没有(引发TypeError):
document.querySelectorAll('table tr:not(tr:nth-child(even))');
var query = (selector) => {
return document.querySelectorAll(selector);
};
try {
var select_a = 'table tr:not(:nth-child(even))';
var select_b = 'table tr:not(tr:nth-child(even))';
query(select_a).forEach((node) => {
node.style.color = 'red';
});
query(select_b).forEach((node) => {
node.style.color = 'blue';
});
} catch (e) {
query('div:nth-child(3)')[0].textContent = e.toString();
}
var query = (selector) => {
return document.querySelectorAll(selector);
};
try {
var select_a = 'table tr:not(:nth-child(even))';
var select_b = 'table tr:not(tr:nth-child(even))';
query(select_a).forEach((node) => {
node.style.color = 'red';
});
query(select_b).forEach((node) => {
node.style.color = 'blue';
});
} catch (e) {
query('div:nth-child(3)')[0].textContent = e.toString();
}
<table>
<tr>
<td>row 1 first-name</td>
<td>row 1 last-name</td>
<td>row-1 email</td>
</tr>
<tr>
<td>row 2 first-name</td>
<td>row 2 last-name</td>
<td>row-2 email</td>
</tr>
<tr>
<td>row 3 first-name</td>
<td>row 3 last-name</td>
<td>row-3 email</td>
</tr>
<tr>
<td>row 4 first-name</td>
<td>row 4 last-name</td>
<td>row-4 email</td>
</tr>
<tr>
<td>row 5 first-name</td>
<td>row 5 last-name</td>
<td>row-5 email</td>
</tr>
</table>
<div>Why does select_a work but not select_b?</div>
<div></div>
答案 0 :(得分:4)
虽然此选择器没有(引发TypeError):
document.querySelectorAll('table tr:not(tr:nth-child(even))');
:not()
仅使用一个“简单选择器”,而tr:nth-child(even)
不是一个选择器。
https://drafts.csswg.org/selectors-3/#simple-selectors-dfn:
一个简单的选择器可以是类型选择器,通用选择器,属性选择器,类选择器,ID选择器或伪类。
任一是这里的重要关键字。这些选择器类型仅允许其中一种,而不是它们的组合。