how to check no of chrectors matched in js code example

Example 1: js character certain count

var str = "Hello Lewes";
var ch = 'e';
 
var count = str.split("e").length - 1;
console.log(count);
 
/*
    Output: 3
*/

Example 2: count value a to b character javascript

const recorrences = ['a', 'b', 'c', 'a', 'b','a']
                .map(i => !!~i.indexOf('a'))
                .filter(i => i)
                .length;
console.log(`recorrences ${recorrences}`) 
//recorrences 3