var str = '13726542608';
var newstr = '';
newstr = str.replace(/s/g, '').replace(/(^d{3})(?=d)/g, "$1 ").replace(/(d{4})(?=d)/g, "$1 ");
console.log(newstr);
var str = '13726542608';
var newstr = '';
newstr = str.replace(/s/g, '').replace(/(^d{3})(?=d)/g, "$1 ").replace(/(d{4})(?=d)/g, "$1 ");
console.log(newstr);