为什么我的函数让 Ghrome Chrome 停止工作？（JavaScript）

Question

I've been training on the CodeWars site and I should have done following exercise:

"Complete the solution so that it splits the string into pairs of two characters. If the string contains an odd number of characters then it should replace the missing second character of the final pair with an underscore ('_')."

BUT my problem is that I've got nothing from the output on the site and when I tried to test my function in Google Chrome console it's just don't return or print anything and the whole browser just stop working...What did I do wrong? There are no "infinite" conditions... What may cause the problem?

Screenshot of output from the CodeWars

 function solution(str){ var result = []; if((str.length % 2) === 0) { for (var i = 0; i < str.length; i + 2){ result.push(str.substr(i, 2)); } } else { for (var i = 0; i < (str.length); i + 2){ result.push(str.substr(i, 2)); } result.push(str.substr(str.length - 1, 1) + '_'); }; return result; };

Answer 1

Your for loops are wrong. They do not increment i . Use i += 2 .

for (let i = 0; i < (str.length); i += 2)