JSFiddle - React, Tailwind, and code Playground
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<pre>
<code>
function isIsogram(str){
let str2 = str.toUpperCase().split('');
str2 = str2.filter( tokken => str2.indexOf(tokken) == str2.lastIndexOf(tokken))
return str2.length == str.length
}
isIsogram("Dermatoglyphics") == true
isIsogram("aba") == false
isIsogram("moOse") == false
</code>
</pre>