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
太老了，但我今天需要做这样的事情，只想事后检查一下。对我来说工作很快。
String.prototype.count = function(substr,start,overlap) {
overlap = overlap || false;
start = start || 0;
var count = 0,
offset = overlap ? 1 : substr.length;
while((start = this.indexOf(substr, start) + offset) !== (offset - 1))
++count;
return count;
};
其他回答
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
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）；
function substrCount( str, x ) {
let count = -1, pos = 0;
do {
pos = str.indexOf( x, pos ) + 1;
count++;
} while( pos > 0 );
return count;
}
这是我的解决方案。我希望这会对某人有所帮助
const countOccurence = (string, char) => {
const chars = string.match(new RegExp(char, 'g')).length
return chars;
}
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>
