在Js中用split function计算字符串中选中字母的总数

Question

I am trying to count the total number of p from any string in js.

my js code:

var sp = "pappa";
var as = sp.split("p");
console.log(as.length);

But it says output: 4 in the console.

even I put an empty string inside sp it shows the value 1 . Why It starts counting from 1 ?

Answer 1

The output is correct. If the separator in split() occurs in first or last position of the string, then empty string is returned. In your case, for separator 'p', str.split('p') returns an array ["", "a", "", "a"] which is of length 4.

Answer 2

As java script creates at least one empty set for every split function you use so if you want to get exact count of any alphabet you need to subtract 1 from the final value.

Answer 3

as Kishor mentioned split returns an array, you can do something like this to achieve the desired behaviour:

var sp = "pappa";
var as = sp.split("p");
var as2 = as.join("");
console.log(as2.length);
// number of "p"s
console.log(sp.length - as2.length);

Answer 4

simply put these line

    var sp = "pappa";
console.log((sp.match(/p/g)).length);