JSFiddle - React, Tailwind, and code Playground
JavaScript
var arr = [1, 1, 1, 0, 0, 0],
startIndex = arr.indexOf(1),
sliceLength = 3,
slice;
while(arr[arr.length - 1] === 0) {
slice = arr.splice(startIndex, sliceLength);
arr.splice.apply(arr, [++startIndex, 0].concat(slice));
console.log(arr);
}