// Get a reference to the current newSegment in state
const { newSegment } = this.state;
// Create a new tricks array based on the old one (just to keep it immuted)
const tricks = [...newSegment.tricks];
// Update the tricks array at index with a new object
tricks[index] = {
    // If the array already had an object, use it's current values
    ...tricks[index],
    // set the name (or whatever property you want)
    name: e.target.value
};
// Now update the state with the updated newSegment (and tricks)
this.setState({
    newSegment: {
        ...newSegment,
        tricks,
    }
});