H ow can i get 123 out of ::123:: in a sentence then store it in a variable.

for example :

hi i am john ::123::.

It will look for :::: tags and get 123 from the it and strip off other words in the sentence. The results would be 123

I am not sure but is this able to work?

$(document).ready(function(){
    var store = $('.div').find(/::([^:]+)::/g);
    alert(store);
});

How can i do this using jquery?