Question:

Implement function ToLowerCase() that has a string parameter str, and returns the same string in lowercase.

Example:

  1. Input: "Hello"
  2. Output: "hello"
  1. Input: "here"
  2. Output: "here"
  4. Input: "LOVELY"
  5. Output: "lovely"

Solution:

  1. /**
  2.  * @param {string} str
  3.  * @return {string}
  4.  */
  5. var toLowerCase = function(str) {
  6.   // ASCII 编码大写小写相差32
  7.   let arr = str.split('');
  8.   let AscCode;
  9.   let maxCode = 'Z'.charCodeAt();
  10.   let minCode = 'A'.charCodeAt();
  11.   for (let i = 0; i < arr.length; i++) {
  12.     // 转换为ASCII码
  13.     AscCode = arr[i].charCodeAt();
  14.     // 大写字母，转小写
  15.     if (maxCode >= AscCode && minCode <= AscCode) {
  16.       arr[i] = String.fromCharCode(AscCode+32);
  17.     }
  18.   }
  19.   return arr.join('');
  20. };

Runtime: 48 ms, faster than 100.00% of JavaScript online submissions for To Lower Case.