JSFiddle - React, Tailwind, and code Playground

JavaScript

function testIndexOfString() {
  var string = "This is a test string";
  
  alert("Index of the string is " + string.indexOf("a"));    
}

function testIndexOfArray() {
  var arr = [1, 2, 4, 2, "abc", "def"];
  alert("Index of the array is " + arr.indexOf("abc"));
}
      
testIndexOfString();
testIndexOfArray();