Reusing simple Javascript Function

Question

I'm new to JS and would like to know how to refactor this simple code so that I can pass in strings to count the number of "e" in a string.

function countE() {
  var count = 0;
  var str = "eee";
  var charLength = str.length;

  for (i =0; i <= charLength; i++){
      if(str.charAt(i) == "e"){
          count++;
      }
  }
   console.log(count);
}

I would like to execute this function where I can do something like this:

countE('excellent elephants');

which would log 5.

developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Functions — Felix Kling
– Felix Kling, Commented Mar 30, 2014 at 20:05
if you want to make your function shorter: function countE(str) { return str.match(/e/g).length; } — friedi
– friedi, Commented Mar 30, 2014 at 20:12

Jason Sperske · Accepted Answer · 2014-03-30 20:07:35Z

2

function countE(str) {
  if(typeof(str)==='undefined') str = 'eee';
  var count = 0;
  var charLength = str.length;

  for (i =0; i <= charLength; i++){
      if(str.charAt(i) == "e"){
          count++;
      }
  }
  console.log(count);
}

edited Mar 30, 2014 at 20:07

Jason Sperske

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answered Mar 30, 2014 at 20:06

Ken Wheeler

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2 Comments

Jason Sperske Over a year ago

Now you can pass an argument or have the function assume 'eee' if no argument is given

Jason Sperske Over a year ago

You could also use the cleaner str = str || "eee" but I thought that the if(typeof(str)==='undefined') str = 'eee'; was easier to understand

friedi · Accepted Answer · 2014-03-30 20:27:55Z

1

If you want to make your function body shorter, you can do the following:

function countE(str) { 
    return str.match(/e/g).length; 
}

And even more sophisticated:

function count(what) {
    return function(str) {
        return str.match(new RegExp(what, 'g')).length;
    };
}

// now you can do the this
var countE = count('e');
var resultE = countE('excellent elephants');

var countL = count('l');
var resultL = countL('excellent elephants');

edited Mar 30, 2014 at 20:27

answered Mar 30, 2014 at 20:20

friedi

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3 Comments

jwize Over a year ago

I think you are over-complicating things for a beginner with your delegates.

friedi Over a year ago

I want to give him some inspiration what is possible with javascript. I know it's too much for a beginner, but maybe in a few days/weeks he goes back here and then learns something new.

jwize Over a year ago

Fair enough, though it might be better with just another parameter. I don't see the point unless you are actually using the delegate.

Jason Baker · Accepted Answer · 2014-03-30 20:08:16Z

0

If I understand your comment correctly, you want to do something like this:

function countE(inString) {
  var count = 0;
  var str = inString ? inString : "eee";
  var charLength = str.length;

  for (i =0; i <= charLength; i++){
      if(str.charAt(i) == "e"){
          count++;
      }
  }
   console.log(count);
}

answered Mar 30, 2014 at 20:08

Jason Baker

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Comments

jwize · Accepted Answer · 2014-03-30 20:26:19Z

0

You can also use a regular expression

function countE(str) {
   var count = str.match(/e/g).length;
   console.log(count);
}

or

function countE(str) {
   console.log(str.match(/e/g).length);
}

edited Mar 30, 2014 at 20:26

answered Mar 30, 2014 at 20:20

jwize

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