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;
}

您可以使用match来定义这样的函数：

String.prototype.count = function(search) {
    var m = this.match(new RegExp(search.toString().replace(/(?=[.\\+*?[^\]$(){}\|])/g, "\\"), "g"));
    return m ? m.length:0;
}

看到这篇帖子。

let str = 'As sly as a fox, as strong as an ox';

let target = 'as'; // let's look for it

let pos = 0;
while (true) {
  let foundPos = str.indexOf(target, pos);
  if (foundPos == -1) break;

  alert( `Found at ${foundPos}` );
  pos = foundPos + 1; // continue the search from the next position
}

相同的算法可以被布置得更短：

let str = "As sly as a fox, as strong as an ox";
let target = "as";

let pos = -1;
while ((pos = str.indexOf(target, pos + 1)) != -1) {
  alert( pos );
}

var str=“堆栈流”；var arr=Array.from（str）；控制台日志（arr）；for（设a=0；a<=arr.length；a++）{变量温度=arr[a]；变量c=0；for（设b=0；b<=arr.length；b++）{如果（温度==arr[b]）{c++；}}console.log（“${arr[a]}计入${c}”）}

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

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);