Conditionally add css class in polymer
update Polymer 1.0
<div class$="[[getClasses(item.completed)]]">
getClasses: function (completed) {
var classes = 'bottom'
if(completed) classes += ' completed';
return classes;
}
Even when completed
could be read from this.item.completed
inside getClasses()
it's important to pass it as parameter from the binding. This way Polymer re-evaluates the function getClasses(item.completed)
each time item.completed
changed.
original - Polymer 0.5
It should look like
<div class="bottom {{ {completed: item.completed } | tokenList }}">
See docs for more details: http://polymer-project.org/docs/polymer/expressions.html#tokenlist
the simplest way to do it:
<template>
<style is="custom-style">
.item-completed-true { background: red; }
</style>
<div class$="bottom item-completed-[[item.completed]]"></div>
</template>
The tokenlist technique was valid in Polymer 0.5, but has been deprecated.
As of Polymer 1.2, the following works:
<dom-module ...>
<template>
<div class$="bottom [[conditionalClass(item.completed)]]"></div>
</template>
<script>
Polymer({
...
conditionalClass: function(completed) {
return completed ? 'completed' : '';
}
});
<script>
</dom-module>
Also see similar question: Polymer 1.0 - Binding css classes