JS查找英文文章中出现频率最高的单词

function counts(article){
 article = article.trim().toUpperCase();
 var array = article.match(/[A-z]+/g);
 article = " "+array.join(" ")+" ";
 var max = 0,word,num = 0,maxword="";
 for(var i = 0; i < array.length; i++) {  
  word = new RegExp(" "+array[i]+" ",'g');
 num = article.match(word).length;
 if(num>max){
  max=num;
  maxword = array[i];
 }
 }
 console.log(maxword+" "+max);
}
counts("Age has reached the end of the beginning of a word. May be guilty in his seems to passing a lot of different life became the appearance of the same day;");