为什么这个 javascript 正则表达式不起作用？
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Why this javascript regex doesn't work?
提问by J4N
I'm doing a small javascript method, which receive a list of point, and I've to read those points to create a Polygon in a google map.
我正在做一个小的 javascript 方法，它接收一个点列表，我必须阅读这些点以在谷歌地图中创建一个多边形。
I receive those point on the form:
我在表格上收到了这些要点：
(lat, long), (lat, long),(lat, long)
(lat, long), (lat, long),(lat, long)
So I've done the following regex:
所以我做了以下正则表达式：
\(\s*([0-9.-]+)\s*,\s([0-9.-]+)\s*\)
I've tested it with RegexPaland the exact data I receive:
我已经用RegexPal和我收到的确切数据对其进行了测试：
(25.774252, -80.190262),(18.466465, -66.118292),(32.321384, -64.75737),(25.774252, -80.190262)
and it works, so why when I've this code in my javascript, I receive null in the result?
它有效，那么为什么当我在我的 javascript 中有这段代码时，我在结果中收到 null？
var polygons="(25.774252, -80.190262),(18.466465, -66.118292),(32.321384, -64.75737),(25.774252, -80.190262)";
var reg = new RegExp("/\(\s*([0-9.-]+)\s*,\s([0-9.-]+)\s*\)/g");
var result = polygons.match(reg);
I've no javascript error when executing(with debug mode of google chrome). This code is hosted in a javascript function which is in a included JS file. This method is called in the OnLoad method.
执行时我没有 javascript 错误（使用 google chrome 的调试模式）。此代码托管在包含的 JS 文件中的 javascript 函数中。该方法在 OnLoad 方法中调用。
I've searched a lot, but I can't find why this isn't working. Thank you very much!
我已经搜索了很多，但我找不到为什么这不起作用。非常感谢你！
回答by Felix Kling
Use a regex literal [MDN]:
使用正则表达式[MDN]：
var reg = /\(\s*([0-9.-]+)\s*,\s([0-9.-]+)\s*\)/g;
You are making two errors when you use RegExp[MDN]:
使用RegExp[MDN]时会犯两个错误：
- The "delimiters"
/are should not be part of the expression - If you define an expression as string, you have to escape the backslash, because it is the escape character in strings
- “分隔符”
/不应该是表达式的一部分 - 如果将表达式定义为字符串，则必须对反斜杠进行转义，因为它是字符串中的转义字符
Furthermore, modifiers are passed as second argument to the function.
此外，修饰符作为第二个参数传递给函数。
So if you wanted to use RegExp(which you don't have to in this case), the equivalent would be:
因此，如果您想使用RegExp（在这种情况下您不必使用），则等效为：
var reg = new RegExp("\(\s*([0-9.-]+)\s*,\s([0-9.-]+)\s*\)", "g");
(and I think now you see why regex literals are more convenient)
（我想现在你明白为什么正则表达式更方便了）
I always find it helpful to copy and past a RegExpexpression in the console and see its output. Taking your original expression, we get:
我总是发现RegExp在控制台中复制和粘贴表达式并查看其输出很有帮助。以你的原始表达，我们得到：
/(s*([0-9.-]+)s*,s([0-9.-]+)s*)/g
which means that the expressions tries to match /, sand gliterally and the parens ()are still treated as special characters.
这意味着表达式会尝试匹配/,s并且g字面上和括号()仍然被视为特殊字符。
Update:.match()returns an array:
更新：.match()返回一个数组：
["(25.774252, -80.190262)", "(18.466465, -66.118292)", ... ]
which does not seem to be very useful.
这似乎不是很有用。
You have to use .exec()[MDN]to extract the numbers:
您必须使用.exec()[MDN]来提取数字：
["(25.774252, -80.190262)", "25.774252", "-80.190262"]
This has to be called repeatedly until the whole strings was processed.
这必须重复调用，直到处理完整个字符串。
Example:
例子：
var reg = /\(\s*([0-9.-]+)\s*,\s([0-9.-]+)\s*\)/g;
var result, points = [];
while((result = reg.exec(polygons)) !== null) {
points.push([+result[1], +result[2]]);
}
This creates an array of arrays and the unary plus (+) will convert the strings into numbers:
这将创建一个数组数组，一元加号 ( +) 会将字符串转换为数字：
[
[25.774252, -80.190262],
[18.466465, -66.118292],
...
]
Of course if you want the values as strings and not as numbers, you can just omit the +.
当然，如果您希望将值作为字符串而不是数字，则可以省略+.
