I'm pretty new to the Vue world and was curious if I'm able to apply 2 computed properties to a :class.
I've tried giving a space to each prop :class="{{prop1}} {{prop2}}"
but on reload the content will all disappear because something seems to be wrong.
Does anybody know if this is possible or if its even a good to do things this way?
Backstory
Im creating an input that will have the :class="{{showWhenButtonClicked}}" and another to give it a green input or a red input classname when the email is not valid.
If there are any details that I'm missing or a better way let me know. Thanks!!
computed: {
validateEmail() {
var re = /^(([^<>()\[\]\\.,;:\s#"]+(\.[^<>()[\]\\.,;:\s#"]+)*)|(".+"))#((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;
return re.test(String(this.emailTo).toLowerCase())
},
showEmailInput() {
return this.sendEmail ? 'hide-show-option' : 'hide-option-input'
},
displayEmailError() {
return this.validateEmail() ? "valid-input" : "not-valid-input"
}
},
<input :class="{{showEmailInput}} {{displayEmailError}}" placeholder="Enter Email..." v-model="emailTo" #blur="{{validateEmail}}" type="email">
You'd use array syntax to apply a list of classes:
<input :class="[showEmailInput, displayEmailError]"/>
Nick's answer is the best one so far. But you can also store the class in a computed variable, which I think cleans up the code:
classList({ sendEmail, validateEmail }) {
return [
sendEmail ? 'hide-show-option' : 'hide-option-input',
validateEmail ? "valid-input" : "not-valid-input"
]
}
OR you can return an object instead, but in this case it's not as succinct as the array
classObject({ sendEmail, validateEmail }) {
return {
'hide-show-option': sendEmail,
'hide-option-input': !sendEmail,
'valid-input': validateEmail,
'not-valid-input': !validateEmail
}
}
When you start to integrate more complex logic in classes, the two options above will make even more sense.
try this
:class="prop1 + ' ' + prop2"
Learning React and trying to cheat off this codepen. I do not understand 2 things.
What is the ... before largebox, flex, and other css classes?
return <div style={{...largebox, ...flex}} key={props.id}
What does the $ do in the css url param? Is it jQuery?
`url(${props.photo})
const FormCard = (props) => (
<div>
{
DATA.map((props) => {
return <div style={{...largebox, ...flex}} key={props.id}>
<div style={{...Photo,backgroundImage: `url(${props.photo})`}}></div>
<div>
<Author author={props.author}/>
<Something bio={props.bio}/>
<AdBox adpic={props.adpic} />
<IconBox />
</div>
</div>
})
}
</div>
)
The three dots '...' are called spread operator, see here https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Spread_syntax
The $ sign is no Jquery but is actually referencing template literals: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Template_literals
Hopefully, the docs are enough as I currently can't find [the link] to [that tutorial] I remember...
Spread operator:
const styleA = { color: 'red' };
const styleB = { background: 'blue' };
const styleC = { ...styleA, ...styleB };
// styleC = {color: "red", background: "blue"}
String Template:
const user = 'Bob';
const greetings = `Hello ${user}`;
// greetings = 'Hello Bob'
for your first question we call it Spread Operator in a simple description for below line :
style={{...largebox, ...flex}}
this is mean copy all property of largebox and flex object into a new object and assing it to style.or this line means :
style={{...Photo,backgroundImage:"myurl}"}
create a new object for me with all property of Photo object and also add a property with name backgroundImage to it. so if Photo is equal to {name:'1.jpg'} the new object is equal to
{name:'1.jpg',backgroundImage:"myUrl"}
Now for your second question, this is template literal and allow you to write variables or call functions inside a string. think we have not this so we must write it like :
backgroundImage: "url(" + props.photo +")"
so as you see it is something like concating props.photo and other strings.but with template literals we can wrap string with backticks and then write variable or function of javascript between ${} like below
backgroundImage: `url(${props.photo})`
then ${props.photo} replace with its value.
I would like to mix the [ngClass] Expressions in Angular, first I want to add an array of classes to my component and then I would also like to add a class based on a Boolean expression.
I can add an array with <li [ngClass]="item.status"> and I can add a class based on a Boolean expression with <li [ngClass]="{active: item.active}">
Note: item.status is an array like item.status=['done', 'progressed']
But how can I mix both styles?
The following doesn't work because only the attribute is duplicate.
<li [ngClass]="item.status" [ngClass]="{active: item.active}">
Thanks in advance
Because you could not have [ngClass] multiple time in same element you could use the combination of [ngClass] and class. When use class in this way with interpolation then you could add several classes as well. Try to use following way.
E.g. HTML
<li class="t-size {{item.status.join(' ')}}" [ngClass]="{'active': item.active }">
E.g. Component
item = {
status : ['done', 'progressed'],
active: true
}
E.g. CSS
.done{
font-weight: bold;
}
.progressed{
color:blue;
}
.t-size{
font-size: 2rem;
}
.active{
background-color: yellowgreen;
}
WORKING DEMO
Hope this will help to you! :)
You can use both as below:
<li [class]="item.status" [ngClass]="{active: item.active}">
You cannot use ngClass more than one time in the single element.
You can do [class.myClass]="booleanExpression", but I don't recommend adding it together with [ngClass] because then you could have a class multiple times.
Instead I would recommend either making [class.myClass]="booleanExpression" for each and every class you use in that HTML-tag (keep in mind the "booleanExpression" can set/unset more than one class so it would not increase the lines of code in your .ts file, only in the template). Or I would make a getter method for [ngClass]:
[ngClass]="liClasses"
get liClasses(): string {
const result = "";
if (conditionOne) { result += " myClassOne"}
if (conditionTwo) { result += " myClassTwo"}
return result;
}
note that solution 1) is more perfomant as getter-methods get triggered on every change-detection and not only when conditionOne or conditionTwo changes.
you can try this code here your app component is
member = true;
paidAmount = true;
setMyClass() {
let classes = {
member: this.someProperty,
paid: this.paidAmount,
};
return classes;
}
where 'member' and 'paid' is class name
and your template use this similar code
<div class="myclass" [ngClass]="setMyClass()">Call to Action</div>
Lets say you have an array that is rendered in a ul with an li for each element and a property on the controller called selectedIndex. What would be the best way to add a class to the li with the index selectedIndex in AngularJS?
I am currently duplicating (by hand) the li code and adding the class to one of the li tags and using ng-show and ng-hide to show only one li per index.
If you don't want to put CSS class names into Controller like I do, here is an old trick that I use since pre-v1 days. We can write an expression that evaluates directly to a class name selected, no custom directives are necessary:
ng:class="{true:'selected', false:''}[$index==selectedIndex]"
Please note the old syntax with colon.
There is also a new better way of applying classes conditionally, like:
ng-class="{selected: $index==selectedIndex}"
Angular now supports expressions that return an object. Each property (name) of this object is now considered as a class name and is applied depending on its value.
However these ways are not functionally equal. Here is an example:
ng-class="{admin:'enabled', moderator:'disabled', '':'hidden'}[user.role]"
We could therefore reuse existing CSS classes by basically mapping a model property to a class name and at the same time keep CSS classes out of Controller code.
ng-class supports an expression that must evaluate to either
A string of space-delimited class names, or
An array of class names, or
A map/object of class names to boolean values.
So, using form 3) we can simply write
ng-class="{'selected': $index==selectedIndex}"
See also How do I conditionally apply CSS styles in AngularJS? for a broader answer.
Update: Angular 1.1.5 has added support for a ternary operator, so if that construct is more familiar to you:
ng-class="($index==selectedIndex) ? 'selected' : ''"
My favorite method is using the ternary expression.
ng-class="condition ? 'trueClass' : 'falseClass'"
Note: Incase you're using a older version of Angular you should use this instead,
ng-class="condition && 'trueClass' || 'falseClass'"
I'll add to this, because some of these answers seem out of date. Here's how I do it:
<class="ng-class:isSelected">
Where 'isSelected' is a javascript variable defined within the scoped angular controller.
To more specifically address your question, here's how you might generate a list with that:
HTML
<div ng-controller="ListCtrl">
<li class="ng-class:item.isSelected" ng-repeat="item in list">
{{item.name}}
</li>
</div>
JS
function ListCtrl($scope) {
$scope.list = [
{"name": "Item 1", "isSelected": "active"},
{"name": "Item 2", "isSelected": ""}
]
}
See: http://jsfiddle.net/tTfWM/
See: http://docs.angularjs.org/api/ng.directive:ngClass
Here is a much simpler solution:
function MyControl($scope){
$scope.values = ["a","b","c","d","e","f"];
$scope.selectedIndex = -1;
$scope.toggleSelect = function(ind){
if( ind === $scope.selectedIndex ){
$scope.selectedIndex = -1;
} else{
$scope.selectedIndex = ind;
}
}
$scope.getClass = function(ind){
if( ind === $scope.selectedIndex ){
return "selected";
} else{
return "";
}
}
$scope.getButtonLabel = function(ind){
if( ind === $scope.selectedIndex ){
return "Deselect";
} else{
return "Select";
}
}
}
.selected {
color:red;
}
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.0.1/angular.min.js"></script>
<div ng-app ng-controller="MyControl">
<ul>
<li ng-class="getClass($index)" ng-repeat="value in values" >{{value}} <button ng-click="toggleSelect($index)">{{getButtonLabel($index)}}</button></li>
</ul>
<p>Selected: {{selectedIndex}}</p>
</div>
I faced a similar problem recently and decided to just create a conditional filter:
angular.module('myFilters', []).
/**
* "if" filter
* Simple filter useful for conditionally applying CSS classes and decouple
* view from controller
*/
filter('if', function() {
return function(input, value) {
if (typeof(input) === 'string') {
input = [input, ''];
}
return value? input[0] : input[1];
};
});
It takes a single argument, which is either a 2-element array or a string, which gets turned into an array that is appended an empty string as the second element:
<li ng-repeat="item in products | filter:search | orderBy:orderProp |
page:pageNum:pageLength" ng-class="'opened'|if:isOpen(item)">
...
</li>
If you want to go beyond binary evaluation and keep your CSS out of your controller you can implement a simple filter that evaluates the input against a map object:
angular.module('myApp.filters, [])
.filter('switch', function () {
return function (input, map) {
return map[input] || '';
};
});
This allows you to write your markup like this:
<div ng-class="muppets.star|switch:{'Kermit':'green', 'Miss Piggy': 'pink', 'Animal': 'loud'}">
...
</div>
The was I recently did that was doing this:
<input type="password" placeholder="Enter your password"
ng-class="{true: 'form-control isActive', false: 'isNotActive'}[isShowing]">
The isShowing value is a value that is located on my controller that gets toggled with the click of a button and the parts between the single parenthesis are classes I created in my css file.
EDIT: I would also like to add that codeschool.com has a free course that is sponsored by google on AngularJS that goes over all of this stuff and then some. There is no need to pay for anything, just signup for an account and get going!
Best of luck to you all!
Ternary operator has just been added to angular parser in 1.1.5.
So the simplest way to do this is now :
ng:class="($index==selectedIndex)? 'selected' : ''"
We can make a function to manage return class with condition
<script>
angular.module('myapp', [])
.controller('ExampleController', ['$scope', function ($scope) {
$scope.MyColors = ['It is Red', 'It is Yellow', 'It is Blue', 'It is Green', 'It is Gray'];
$scope.getClass = function (strValue) {
switch(strValue) {
case "It is Red":return "Red";break;
case "It is Yellow":return "Yellow";break;
case "It is Blue":return "Blue";break;
case "It is Green":return "Green";break;
case "It is Gray":return "Gray";break;
}
}
}]);
</script>
And then
<body ng-app="myapp" ng-controller="ExampleController">
<h2>AngularJS ng-class if example</h2>
<ul >
<li ng-repeat="icolor in MyColors" >
<p ng-class="[getClass(icolor), 'b']">{{icolor}}</p>
</li>
</ul>
<hr/>
<p>Other way using : ng-class="{'class1' : expression1, 'class2' : expression2,'class3':expression2,...}"</p>
<ul>
<li ng-repeat="icolor in MyColors">
<p ng-class="{'Red':icolor=='It is Red','Yellow':icolor=='It is Yellow','Blue':icolor=='It is Blue','Green':icolor=='It is Green','Gray':icolor=='It is Gray'}" class="b">{{icolor}}</p>
</li>
</ul>
You can refer to full code page at ng-class if example
I am new to Angular but have found this to solve my issue:
<i class="icon-download" ng-click="showDetails = ! showDetails" ng-class="{'icon-upload': showDetails}"></i>
This will conditionally apply a class based on a var.
It starts off with a icon-download as a default, the using ng-class, I check the status of showDetails if true/false and apply class icon-upload. Its working great.
Hope it helps.
This works like a charm ;)
<ul class="nav nav-pills" ng-init="selectedType = 'return'">
<li role="presentation" ng-class="{'active':selectedType === 'return'}"
ng-click="selectedType = 'return'"><a href="#return">return
</a></li>
<li role="presentation" ng-class="{'active':selectedType === 'oneway'}"
ng-click="selectedType = 'oneway'"><a href="#oneway">oneway
</a></li>
</ul>
This will probably get downvoted to oblivion, but here is how I used 1.1.5's ternary operators to switch classes depending on whether a row in a table is the first, middle or last -- except if there is only one row in the table:
<span class="attribute-row" ng-class="(restaurant.Attributes.length === 1) || ($first ? 'attribute-first-row': false || $middle ? 'attribute-middle-row': false || $last ? 'attribute-last-row': false)">
</span>
This is in my work multiple conditionally judge:
<li ng-repeat='eOption in exam.examOptions' ng-class="exam.examTitle.ANSWER_COM==exam.examTitle.RIGHT_ANSWER?(eOption.eoSequence==exam.examTitle.ANSWER_COM?'right':''):eOption.eoSequence==exam.examTitle.ANSWER_COM?'wrong':eOption.eoSequence==exam.examTitle.RIGHT_ANSWER?'right':''">
<strong>{{eOption.eoSequence}}</strong> |
<span ng-bind-html="eOption.eoName | to_trusted">2020 元</span>
</li>
Here is another option that works well when ng-class can't be used (for example when styling SVG):
ng-attr-class="{{someBoolean && 'class-when-true' || 'class-when-false' }}"
(I think you need to be on latest unstable Angular to use ng-attr-, I'm currently on 1.1.4)
well i would suggest you to check condition in your controller with a function returning true or false .
<div class="week-wrap" ng-class="{today: getTodayForHighLight(todayDate, day.date)}">{{day.date}}</div>
and in your controller check the condition
$scope.getTodayForHighLight = function(today, date){
return (today == date);
}
partial
<div class="col-md-4 text-right">
<a ng-class="campaign_range === 'thismonth' ? 'btn btn-blue' : 'btn btn-link'" href="#" ng-click='change_range("thismonth")'>This Month</a>
<a ng-class="campaign_range === 'all' ? 'btn btn-blue' : 'btn btn-link'" href="#" ng-click='change_range("all")'>All Time</a>
</div>
controller
$scope.campaign_range = "all";
$scope.change_range = function(range) {
if (range === "all")
{
$scope.campaign_range = "all"
}
else
{
$scope.campaign_range = "thismonth"
}
};
If you are using angular pre v1.1.5 (i.e. no ternary operator) and you still want an equivalent way to set a value in both conditions you can do something like this:
ng-class="{'class1':item.isReadOnly == false, 'class2':item.isReadOnly == true}"
If you having a common class that is applied to many elements you can create a custom directive that will add that class like ng-show/ng-hide.
This directive will add the class 'active' to the button if it's clicked
module.directive('ngActive', ['$animate', function($animate) {
return function(scope, element, attr) {
scope.$watch(attr.ngActive, function ngActiveWatchAction(value){
$animate[value ? 'addClass' : 'removeClass'](element, 'active');
});
};
}]);
More info
Just adding something that worked for me today, after much searching...
<div class="form-group" ng-class="{true: 'has-error'}[ctrl.submitted && myForm.myField.$error.required]">
Hope this assists in your successful development.
=)
Undocumented Expression Syntax : Great Website Link... =)
Check this.
The infamous AngularJS if|else statement!!!
When I started using Angularjs, I was a bit surprised that I couldn’t find an if/else statement.
So I was working on a project and I noticed that when using the if/else statement, the condition shows while loading.
You can use ng-cloak to fix this.
<div class="ng-cloak">
<p ng-show="statement">Show this line</span>
<p ng-hide="statement">Show this line instead</span>
</div>
.ng-cloak { display: none }
Thanks amadou
You can use this npm package. It handles everything and has options for static and conditional classes based on a variable or a function.
// Support for string arguments
getClassNames('class1', 'class2');
// support for Object
getClassNames({class1: true, class2 : false});
// support for all type of data
getClassNames('class1', 'class2', ['class3', 'class4'], {
class5 : function() { return false; },
class6 : function() { return true; }
});
<div className={getClassNames({class1: true, class2 : false})} />
I understand this question id for angular, but if anyone is using React or a React-Based Framework (Amplify, NextJS, Serverless, etc.) The solution is significantly easier. The most performant way is with a ternary operator like so:
<div className={condition ? "classnameiftrue" : "classnameiffalse"}>
You can use this strategy to animate the tree if using useState() as each time the state changes it will reload that conditional with the new value.