How to show placeholder instead of the state's value at pageload? - javascript

I am trying to show the placeholder of an input instead of its state value. When I load the page it shows a blank select box, which makes sense because the testType state is null when the page first loads. How can I get it to just show the placeholder instead of the null state?
function RandomSelection(props) {
const [testType, setTestType] = useState(null);
const handleTestType = value => {
setTestType(value);
};
return(
<Select
placeholder="Test Type..."
value={testType}
onChange={handleTestType}
>
<Option value="Option 1">
Option 1
</Option>
<Option value="Option 2">Option 2</Option>
<Option value="Option 3">Option 3</Option>
</Select>
) }
The Select option is from Ant Design, however I feel the solution to this may apply to Material-UI and Bootstrap as well.

Since you never show the import path, and your code works perfectly fine using Antd's Select, my guess is that you're using the Select from MUI (partly because you also tagged material-ui in your question). So check your import path, because MUI Select placeholder is set by the label prop:
Right
import { Select } from 'antd';
Wrong
import { Select } from '#mui/material';

In const [testType, setTestType] = useState(null);, set useState's default value to what you want the placeholder to be instead of null.

Related

the default option is not coming in select tag

enter image description hereI want to add the default option select in select tag but it taking the default value from the api data
Here the select should come rather than taking default value from api
By selected props you can make it default selected:
(Note: I am pasting example please change as per your requirement.)
<select name="plan" id="plan">
<option value="free">Free</option>
<option value="starter" selected>Starter </option>
<option value="professional">Professional</option>
<option value="corporate">Corporate</option>
</select>
So Here starter (second one) will be default selected.

select method to restore to default value

Iam trying to do something that look easy but i cant find any soulotion,
i have <select> tag with 5 <option> all i want to do is when i click a button (have function inside of it) the select tag will be the default one (the first one)
for example :
<select className={'smallSelect'} onChange={appliances}>
<option defaultValue =''>Add</option> {/* The default */}
<option value='<Fan/>'>Air-Conditioner</option>
<option value='<HotTub/>'>boilermaker</option>
<option value='<Bulb/>'>lamp</option>
<option value='<Radio/>'>stereo system</option>
</select><br/> {/* After clicking the button the option will be the default */}
<button className={'myButton'} onClick={newAppliances}>Add</button>
I assume the button onClick event calls the function newAppliances?
You need to set the select value to ''. So add something like this at the end of your newAppliances function.
document.getElementById('.smallSelect').value = '';
See this:
How do I programmatically set the value of a select box element using JavaScript?
For React
The above solution is for normal javascript, if you want to do the react way, read this:
React JSX: selecting "selected" on selected <select> option

ReactJS: Select with default value from props without onChange event?

So, I was just wondering if I absolutely need to have a onChange event handler on a select component in React?
I have a prop passing in the default value on the option I want selected. It works no problem if I have:
<select
value={this.props.defaultValue}
>
<option value="a">A</option>
<option value="b">B</option>
</select>
Except, it is static as I am sure you are familiar with the error:
Warning: Failed form propType: You provided a `value` prop to a form field without an `onChange` handler.
This will render a read-only field.
As I am getting the value using Jquery, I don't need a state or any passing between child and parent...
Is there a simple way to allow the select to get a default value from props and still operate as a normal select where changing an option changes the value I can grab with jquery, or do I have to have a state, and a onChange handler?
Thanks!
What I have already tried:
<select
defaultValue={this.props.defaultValue} // just returns the first option
>
<options etc.>
</select>
Also, I would rather not use an external package like React-Select... I just want to have a default value and a normal select...
As #julien mentions, you can use ref instead of JQuery to get the current value of the select in an uncontrolled component:
class MySelect extends React.Component {
constructor(props) {
super(props);
this.state = { currentValue: this.props.defaultValue };
}
updateValue() {
this.setState({ currentValue: this.refs.myselect.value });
}
render () {
return (
<div>
<div>
<button className="current" onClick={this.updateValue.bind(this)}>{this.state.currentValue}</button>
</div>
<select ref="myselect" defaultValue={this.props.defaultValue}>
<option value="a">A</option>
<option value="b">B</option>
<option value="c">C</option>
</select>
</div>
);
}
}
For the other part, defaultValue should work just as you were trying.
Check this example fiddle: https://jsfiddle.net/y64gbhf8/1/
you can try Uncontrolled Components
you don't need to write event handler for state update,DOM will handle it,
then you can use a ref to get form values from the DOM

Angular 2 - setting default value in dropdown when default is hard coded

I have the following dropdown. I want to set All Patients as the default value.
<select [(ngModel)]="searchModel.careprovider">
<option [value]="0">All Pateints</option>
<option *ngFor="let user of practiceUsers" [value]="user._id.$oid">
{{user.dn}}
</option>
</select>
My model is declared this way:
searchModel: any = { location: null, practice: null, name: '', careProvider: 0 };
I set the practiceUsers this way:
this._practice.getUsers(this.searchModel.practice).subscribe(result => {
this.practiceUsers = result;
this.searchModel.careProvider = 0;
});
No matter how I change it I always just get a blank option as the default. I've tried adding an object to the this.practiceUsers array after it is loaded, then setting the model value. I've tried setting the model value with and without quotes to see if a number or string made a difference. Everything I try still results in the default being the blank option.
In Angular 1 I would have used ng-options, but that is no longer available for Angular 2, and every example I find shows to use the ngFor for dropdowns.
Object attributes are case sensitive, in your object, attribute is called careProvider, but in your template, you are using searchModel.careprovider with lowercase p. I think you also have to use NgValue directive instead of value because you are using NgModel directive. So, this should work: it is not working
<select [(ngModel)]="searchModel.careProvider">
<option [ngValue]="0">All Pateints</option>
<option *ngFor="let user of practiceUsers" [ngValue]="user._id.$oid">
{{user.dn}}
</option>
</select>
Try to use [selected] attribute. I solved similar problem this way:
<select>
<option *ngFor="let option of options" value="{{option.id}}" [selected]="option === selectedOption">
{{option.name}}
</option>
</select>
I hope this helps a little
<select class="form-control" id="policeid_country_id" name="policeid_country_id" formControlName="policeid_country_id">
<option [ngValue]="null">Select</option>
<option [ngValue]="country.id" *ngFor="let country of countries">{{country.country}}</option>
</select>

why does ReactJS suppress changes in <input> elements but not in e.g. <select> elements

Here's a SSCCE to illustrate my question:
const React = require('react');
const App = React.createClass({
getInitialState: function() {
return {
text: 'foo',
selection: 'apples'
};
}
, render: function() {
return (
<div>
<div>
<input type='text' value={this.state.text}/>
</div>
<select>
<option value='bananas' selected={this.state.selection==='bananas'}>bananas</option>
<option value='apples' selected={this.state.selection==='apples'} >apples </option>
<option value='onions' selected={this.state.selection==='onions'} >onions </option>
</select>
</div>
);
}
});
The above React component when rendered, displays (unsurprisingly) the below view:
The model is taken into account as expected.
When one tries to type into the <input> element nothing happens. The explanation is that ReactJS uses one way flow and you have to add onchange listeners to update the model etc. That's fine.
What I don't get is why ReactJS prevents the <input> element from changing and forces it to always reflect the model value that flowed down to it, whereas at the same time it allows me to change the <select> element:
Apparently my mental model is lacking. What am I missing ?
You're hard coding the value to be this.state.text so it will always be the same on every keystroke. See the forms documentation.
What you have here is a controlled <input> element and an uncontrolled <select> element. See controlled components
Its possible to create an uncontrolled text input by not specifying the value prop.
And its possible to create a controlled select element by specifying the value prop.
<select value={this.state.value}>
<option value="bannanas">bananas</option>
<option value="apples">apples</option>
<option value="onions">onions</option>
</select>
There is documentation explaining specifically this. See here

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