JSFiddle - React, Tailwind, and code Playground
JavaScript
var arr = ['a','b','c','d','a', 'a'], i, len;
var lastIndex = -1;
var newIndex = -1;
var outArray = [];
for (i = 0, len = arr.length; i < len; i++) {
newIndex = arr.indexOf('a', i)
if (!(newIndex == lastIndex )) {
lastIndex = newIndex;
outArray.push(newIndex);
} else {
continue;
//lastIndex = newIndex;
}
console.log(lastIndex)
}
console.log(outArray)