1/** 2 * Insert `insertArr` inside `target` at `insertIndex`. 3 */ 4export function arrayInsert<T>(target: T[], insertIndex: number, insertArr: T[]): T[] { 5 const before = target.slice(0, insertIndex); 6 const after = target.slice(insertIndex); 7 return before.concat(insertArr, after); 8} 9 10