30-seconds-of-code/snippets/isIsogram.md

title, tags

title	tags
isIsogram	string, intermediate

Creates a function that accepts a string parameter and output whether its an isogram or not.

• Use String.toLowerCase() to convert the string to lowercase letters.
• Use String.prototype.split(), String.prototype.indexOf() and Array.prototype.every() to split the string into substrings, run a test for all the elements in that array and finally return the index of first occurence of a specified value in a string.
• Function returns true if the string is an isogram (that is no letter is repeated) else returns false.
• Returns false is called with no parameter.

const isIsogram = (str = null) => {
  if(str == null) return false;
  str = str.toLowerCase();
  return str.split("").every((c, i) => str.indexOf(c) === i);
}		

isIsogram("Dermatoglyphics"); // true
isIsogram("aba"); // false
isIsogram("moOse"); // false
isIsogram(); // false