获取 JavaScript 中某个字符出现的次数
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Get number of occurrences of a character in JavaScript
提问by Upvote
I have a string that devides some data using ','. Now I want to count the occurences of ','in that string. I tried:
我有一个字符串，它使用','. 现在我想计算该','字符串中 的出现次数。我试过：
var match = string.match('/[,]/i');
But this gives me null If I try to get the length of the match array. Any ideas?
但这给了我 null 如果我尝试获取匹配数组的长度。有任何想法吗？
回答by Chandu
If you need to check the occurances of a simple pattern as "," then better don't use regular expressions.
如果您需要将简单模式的出现情况检查为“,”，那么最好不要使用正则表达式。
Try:
尝试：
var matchesCount = string.split(",").length - 1;
回答by jfriend00
Remove the quotes and add the g flag:
删除引号并添加 g 标志：
var str = "This, is, another, word, followed, by, some, more";
var matches = str.match(/,/g);
alert(matches.length); // 7
jsfiddle here: http://jsfiddle.net/jfriend00/hG2NE/
jsfiddle在这里：http: //jsfiddle.net/jfriend00/hG2NE/
回答by joeytwiddle
This gistclaimed that regexp was the most efficient technique.
这个要点声称正则表达式是最有效的技术。
Edit:However the performance benchmarkprovided by Jobin the comments suggest that the splittechnique is now faster. So I would recommend that nowadays.
编辑：然而，Job在评论中提供的性能基准表明该技术现在更快了。所以我会推荐现在。split
But anyway, if you do go with the regexp approach, you should be aware that if there are no matches, then String::match()returns null, and not an empty array as you might expect:
但无论如何，如果您确实使用 regexp 方法，您应该知道如果没有匹配项，则String::match()返回 null，而不是您可能期望的空数组：
> 'foo'.match(/o/g)
[ 'o', 'o' ]
> 'foo'.match(/o/g).length
2
> 'foo'.match(/x/g)
null
> 'foo'.match(/x/g).length
TypeError: Cannot read property 'length' of null
One simple way to deal with this is to substitute an empty array if the result is null:
处理此问题的一种简单方法是，如果结果为 null，则替换为空数组：
var count = (string.match(/,/g) || []).length;
Or this avoids creating the empty array, but requires two lines of code:
或者这样可以避免创建空数组，但需要两行代码：
var match = string.match(/,/g);
var count = match ? match.length : 0;
回答by agent-j
Count number of matches of a regex in Javascript
you need the /gglobal flag
你需要/g全球旗帜
Edit: I didn't need the 'ticks' below.
编辑：我不需要下面的“勾号”。
var count = string.match(/,/g).length;
回答by rubergly
This gives nullbecause '/[,]/i'is not a regex. As explained at the MDN, if a non-regex is passed to string.match, then it will be converted to a regex using new Regex(obj).
这给出了null因为'/[,]/i'不是正则表达式。如MDN 中所述，如果将非正则表达式传递给string.match，则它将使用 转换为正则表达式new Regex(obj)。
What you want is to pass the actual regex object, /[,]/i(or simply /,/i). "1,2,3".match(/,/i)will work as you expect in terms of matching.
你想要的是传递实际的正则表达式对象，/[,]/i（或简单地/,/i）。"1,2,3".match(/,/i)在匹配方面将按您的预期工作。
However, as Cybernate pointed out, a regex is overkill for this kind of problem. A better solution is to split the string:
然而，正如 Cybernate 所指出的，正则表达式对于这类问题来说太过分了。更好的解决方案是拆分字符串：
var str = "1,2,3,4,5";
var len = str.split(",").length - 1;
回答by Rahul Ranjan
function get_occurrence(varS,string){//Find All Occurrences
c=(string.split(varS).length - 1);
return c;
}
string="Hi, 1,2,3";
console.log(get_occurrence(",",string));
Use get_occurrence(varS,string) to find occurrence of both characters and string in a String.
使用 get_occurrence(varS,string) 查找字符串中字符和字符串的出现。
回答by Sumant Singh
Use the following code to divide some data using ',' from a statement:
使用以下代码从语句中使用“,”分割一些数据：
var str = "Stack,Overflow,best,for,coder"
var matchesCount = str.split(",").length;
var vallueArray = str.split(',', matchesCount);
var value1= "";
for (var i = 0 ; i < vallueArray.length; i++) {
value1= value1+ vallueArray [i] + " ";
}
document.getElementById("txt1").value = value1;
