JavaScript: Count instances of specific integers in a string

Question

OKAY, so I have a bunch of numbers in a div, lets say something like...

<div id="countme">7, 5, 6, 0, 3, 0, 5, 3, 3, 2, 8</div>

And I want to use JavaScript to return...

The specific number, and
The number of times that number occurred in the div

Example Output: "(2,0),(1,2),(3,3),(2,5),(1,6),(1,7),(1,8)"

Explained: Zero appears two times, two appears one time, three appears three times, etc...

I've tried the following...

var str = document.getElementById('countme').innerText;
var match = str.match(/7/g);
var match1 = str.match(/5/g);
alert(match.length);
alert(match1.length);

But I need it to display the number it searched for, and I need everything to be in one alert.

Any thoughts?

Thanks! :)

omarjmh · Accepted Answer · 2016-04-27 19:29:32Z

1

JSBIN: https://jsbin.com/tesezoz/1/edit?js,console

var str = "7, 5, 6, 0, 3, 0, 5, 3, 3, 2, 8";

// first get the numbers
var m = str.split(', ').map(Number);

// turn it into an object with counts for each number:

var c = m.reduce(function(a, b) {
  a[b] = ++a[b] || 1;
  return a;
}, {});

// now you have an object that you can check for the count
// which you can alert... its the c variable

answered Apr 27, 2016 at 19:29

omarjmh

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1 Comment

Michael L. Over a year ago

That's logically the same as the solution I was about to post; however, as a style critique, I try to avoid the pre-increment operator (e.g. ++a[b]). It tends towards poor readability, as do meaningless variable names such as 'a' and 'b' (except for where it's more or less idiomatic, such as sorting functions, but even then I'd probably prefer more descriptive names).

Reinstate Monica Cellio · Accepted Answer · 2016-04-27 19:35:19Z

0

Try this...

var str = "7, 5, 6, 0, 3, 0, 5, 3, 3, 2, 8";
str = str.replace(/\s/g, "");
str = str.split(",");

var result = {};

str.forEach(function(value) {
    if (result[value]) {
        result[value]++;
    }
    else {
        result[value] = 1;
    }
});

var output = "";

for(value in result) {
    output += (output == "" ? "" : ",") + "(" + value + "," + result[value] +")";
}

alert(output);

It splits the string and removes any whitespace, so you're left with an array (and no assumption that the delimiter is consistent).

It then creates an object representing each value and the count.

It finally converts that into an output, similar to the one in your example.

answered Apr 27, 2016 at 19:35

Reinstate Monica Cellio

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Comments

Vishnu Ravi · Accepted Answer · 2016-04-27 19:34:21Z

0

Here is the Answer

var str    = document.getElementById('countme').innerText;
var array  = JSON.parse("[" + str+ "]");
var counts = {};
array.forEach(function(x) { counts[x] = (counts[x] || 0) + 1; });
console.log(counts);

answered Apr 27, 2016 at 19:34

Vishnu Ravi

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Comments

Blue · Accepted Answer · 2016-04-27 20:58:35Z

0

I think this is almost as efficient as you can get. It also serves as a general count unique matches method:

var testString = document.getElementById('countme').innerText;
count = {}; 
var regX = /(\d+)/g;
var res;
while (res = regX.exec(testString )) {
    count[res[0]] = (count[res[0]] !== undefined ? ++count[res[0]] : 1)
};

answered Apr 27, 2016 at 20:58

Blue

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