freeCodeCamp-截断字符串。行使

Question

我正在尝试解决基本算法脚本问题：截断字符串；但不能正常工作...

 let truncateString = (str, num) => {
   return (str.length <= num ? str : str.slice(0, num > 3 ? num - 3 : num) + '...');
 };


truncateString("A-tisket a-tasket A green and yellow basket", 8);

// running tests
truncateString("A-tisket a-tasket A green and yellow basket", 8) should return "A-tisket...".
truncateString("Peter Piper picked a peck of pickled peppers", 11) should return "Peter Piper...".
// tests completed

Answer 1

比您的代码还要简单-稍微更改三元运算符：

let truncateString = (str, num) => str.length > num ? str.slice(0, num) + "..." : str;

console.log(truncateString("A-tisket a-tasket A green and yellow basket", 8));
console.log(truncateString("Peter Piper picked a peck of pickled peppers", 11));

Answer 2

在这里：（有效）

let truncateString = (str, num) => {
   return (str.length <= num ? str : str.slice(0, num) + '...');
 };

Answer 3

    let truncateString = (str, num) => {
       const x = str.length,
         y = num,
         min = y ^ ((x ^ y) & -(x < y)); 
       return str.slice(0, min) + (!(y-min) && '...');
    };