onChange event for selects not handling value correctly

[Swazimodo]

The value property for a Select component has a type definition of Array<string | number> | string | number. However, if you look at the onChange event event.target.value has a type definition of just string. I'm trying to get a multiselect this working but I found this confusing and suspect it's a bug.

• This is a v1.x issue
• I have searched the issues of this repository and believe that this is not a duplicate.

Expected Behavior

I believe the value you get from the onChange event should match the type you can supply in the component props.

Current Behavior

I have not fully tested this but at least the type returned is only a string.

Steps to Reproduce

Here is code similar to what I'm doing.

export interface IOption {
    label: string;
    value: string | number;
    fixedValue?: boolean;
    disabled?: boolean;
}

interface IComponentProps {
    options: IOption[];
	values: Array<string | number> | string | number;
}

<Select                
	multiple
	onChange={this.handleChange}
	value={this.props.values}
>
	{this.props.options.map(this.renderOption)}
</Select>

renderOption = (x: IOption, i: number) => {
	return <MenuItem key={i} value={x.value}>{x.label}</MenuItem>
}

handleChange = (event: React.ChangeEvent<HTMLSelectElement>) => {
	console.log('onChange', event.target.value);
}

Context

Right now creating a multiselect feels like it takes too much legwork and from what I have seen people are using other packages to make it work.

Your Environment

Tech	Version
Material-UI	v^1.1.0
React	v^16.3.2
Chrome	v68.0.3440.106
TypeScript	v2.8.4

Update

I was able to confirm this is only a typescript issue. In the onChange event event.target.value will give you an array if you have multiple items selected.

[skirunman]

This is a problem for us as well and we are not using Typescript.

[mhafer]

Following

[mbrookes]

@mhafer

[eps1lon]

Closing this in favor of #16065 which targets 4.x. We don't plan on supporting 1.x types any longer.