如何计算特定字符串在另一个字符串中出现的次数。例如,这就是我试图在Javascript中做的事情:

var temp = "This is a string.";
alert(temp.count("is")); //should output '2'

当前回答

Leandro Batista的答案:只是正则表达式有问题。

“使用严格”;var dataFromDB=“testal”;$('input[name=“tbInput”]').on(“change”,function(){var charToTest=$(this).val();var howManyChars=charToTest.length;var nrMatches=0;如果(howManyChars!==0){charToTest=charToTest.charAt(0);var regexp=新regexp(charToTest,'gi');var arrMatches=dataFromDB.match(正则表达式);nrMatches=arrMatches?arrMatches.length:0;}$('#result').html(nrMatches.toString());});<script src=“https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js“></script><div class=“main”>你想数什么<input type=“text”name=“tbInput”value=“”><br/>出现次数=<span id=“result”>0</span></div>

其他回答

函数countInstance(字符串,单词){返回字符串.split(word).length-1;}console.log(countInstance(“This is a string”,“is”))

只需编码打高尔夫球丽贝卡·切尔诺夫的解决方案:-)

alert(("This is a string.".match(/is/g) || []).length);

我认为regex的目的与indexOf有很大不同。indexOf只需查找某个字符串的出现,而在正则表达式中,您可以使用[a-Z]之类的通配符,这意味着它将查找单词中的任何大写字符,而无需说明实际字符。

例子:

var index=“This is a string”.indexOf(“is”);console.log(索引);var length=“This is a string”.match(/[a-z]/g).length;//其中[a-z]是正则表达式通配符,这就是为什么其速度较慢的原因console.log(长度);

试试看

<?php 
$str = "33,33,56,89,56,56";
echo substr_count($str, '56');
?>

<script type="text/javascript">
var temp = "33,33,56,89,56,56";
var count = temp.match(/56/g);  
alert(count.length);
</script>
var mystring = 'This is the lorel ipsum text';
var mycharArray = mystring.split('');
var opArr = [];
for(let i=0;i<mycharArray.length;i++){
if(mycharArray[i]=='i'){//match the character you want to match
    opArr.push(i);
  }}
console.log(opArr); // it will return matching index position
console.log(opArr.length); // it will return length