Retrieving value from <select> with multiple option in React

Answer 1

In the case you would like to keep track of the selected options while the form is being completed:

handleChange(e) {
    // assuming you initialized the default state to hold selected values
    this.setState({
        selected:[].slice.call(e.target.selectedOptions).map(o => {
            return o.value;
        });
    });
}

selectedOptions is an array-like collection/list of elements related to the DOM. You get access to it in the event target object when selecting option values. Array.prototype.sliceand call allows us to create a copy of it for the new state. You could also access the values this way using a ref (in case you aren't capturing the event), which was another answer for the question.