Javascript 如何在javascript中计算字符串的行数
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How to count the number of lines of a string in javascript
提问by Itzik984
I want to count the number of lines in a string
我想计算字符串中的行数
i tried to use this stackoverflow answer :
我尝试使用这个 stackoverflow 答案：
lines = str.split("\r\n|\r|\n");
return lines.length;
on this string(which was originally a buffer):
在这个字符串（它最初是一个缓冲区）上：
GET / HTTP/1.1
Host: localhost:8888
Connection: keep-alive
Cache-Control: max-age=0
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_2) AppleWebKit/535.2 (KHTML,like Gecko) Chrome/15.0.874.121 Safari/535.2
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3
and for some reason i got lines='1'.
出于某种原因，我得到了lines='1'。
any idea how to make it work?
知道如何使它工作吗？
回答by Pavan
Using a regular expression you can count the number of lines as
使用正则表达式，您可以将行数计算为
str.split(/\r\n|\r|\n/).length
Alternately you can try split method as below.
或者，您可以尝试如下拆分方法。
var lines = $("#ptest").val().split("\n");
alert(lines.length);
working solution: http://jsfiddle.net/C8CaX/
工作解决方案：http: //jsfiddle.net/C8CaX/
回答by ngryman
Another short, potentially more performant than split, solution is:
另一个简短的，可能比拆分性能更高的解决方案是：
const lines = (str.match(/\n/g) || '').length + 1
回答by dxh
To split using a regex use /.../
使用正则表达式拆分 /.../
lines = str.split(/\r\n|\r|\n/);
回答by Aadit M Shah
Hmm yeah... what you're doing is absolutely wrong. When you say str.split("\r\n|\r|\n")it will try to find the exact string "\r\n|\r|\n". That's where you're wrong. There's no such occurance in the whole string. What you really want is what David Hedlund suggested:
嗯是的...你在做什么是完全错误的。当你说它str.split("\r\n|\r|\n")会尝试找到确切的字符串"\r\n|\r|\n"。那就是你错了。整个字符串中没有这种情况。你真正想要的是 David Hedlund 的建议：
lines = str.split(/\r\n|\r|\n/);
return lines.length;
The reason is that the split method doesn't convert strings into regular expressions in JavaScript. If you want to use a regexp, use a regexp.
原因是 split 方法不会将字符串转换为 JavaScript 中的正则表达式。如果要使用正则表达式，请使用正则表达式。
回答by jperelli
I made a performance test comparing split with regex, with a string and doing it with a for loop.
我做了一个性能测试，将 split 与正则表达式、字符串和 for 循环进行比较。
It seems that the for loop is the fastest.
似乎for循环是最快的。
NOTE: this code 'as is' is not useful for windows nor macos endline, but should be ok to compare performance.
注意：此代码“按原样”对 windows 或 macos 端线没有用，但应该可以比较性能。
Split with string:
用字符串分割：
split('\n').length;
Split with regex:
用正则表达式拆分：
split(/\n/).length;
Split using for:
拆分用于：
var length = 0;
for(var i = 0; i < sixteen.length; ++i)
if(sixteen[i] == s)
length++;
回答by Joe
There are three options:
共有三个选项：
Using jQuery (download from jQuery website) - jquery.com
使用 jQuery（从jQuery 网站下载） - jquery.com
var lines = $("#ptest").val().split("\n");
return lines.length;
Using Regex
使用正则表达式
var lines = str.split(/\r\n|\r|\n/);
return lines.length;
Or, a recreation of a for each loop
或者，为每个循环重新创建一个
var length = 0;
for(var i = 0; i < str.length; ++i){
if(str[i] == '\n') {
length++;
}
}
return length;
回答by Sandeep G B
回答by Krishna Kumar Jangid
<script type="text/javascript">
var multilinestr = `
line 1
line 2
line 3
line 4
line 5
line 6`;
totallines = multilinestr.split("\n");
lines = str.split("\n");
console.log(lines.length);
</script>
thats works in my case
这在我的情况下有效
回答by hashed_name
Better solution, as str.split("\n") function creates new array of strings split by "\n" which is heavier than str.match(/\n\g). str.match(/\n\g) creates array of matching elements only. Which is "\n" in our case.
更好的解决方案，因为 str.split("\n") 函数创建了由 "\n" 分割的新字符串数组，这比 str.match(/\n\g) 重。str.match(/\n\g) 仅创建匹配元素的数组。在我们的例子中是“\n”。
var totalLines = (str.match(/\n/g) || '').length + 1;
