Đếm số lần xuất hiện của mỗi ký tự trong chuỗi với JavaScript?

Dùng mảng lưu tần suất từng ký tự. Nếu ký tự trùng, tăng 1, ngược lại gán 1.

Giả sử chuỗi:

var sentence = "My name is John Smith";

Mã đếm xuất hiện:

Ví dụ

var sentence = "My name is John Smith"; sentence=sentence.toLowerCase(); var noOfCountsOfEachCharacter = {}; var getCharacter, counter, actualLength, noOfCount; for (counter = 0, actualLength = sentence.length; counter < actualLength; ++counter) { getCharacter = sentence.charAt(counter); noOfCount = noOfCountsOfEachCharacter[getCharacter]; noOfCountsOfEachCharacter[getCharacter] = noOfCount ? noOfCount + 1: 1; } for (getCharacter in noOfCountsOfEachCharacter) { if(getCharacter!=' ') console.log("Character="+getCharacter + " Occurrences=" + noOfCountsOfEachCharacter[getCharacter]); }

Chạy: node fileName.js. File demo40.js.

Kết quả

PS C:\Users\Amit\JavaScript-code> node demo40.js Character=m Occurrences=3 Character=y Occurrences=1 Character=n Occurrences=2 Character=a Occurrences=1 Character=e Occurrences=1 Character=i Occurrences=2 Character=s Occurrences=2 Character=j Occurrences=1 Character=o Occurrences=1 Character=h Occurrences=2 Character=t Occurrences=1