Backbone.js previous Model
Last Updated :
13 Jun, 2022
The Backbone.js previous model is used to get the previous value of the changed attributes, while the change event occurs in a given model. It will return the actual attribute of the model.
Syntax:
Backbone.Model.previous(attribute);
Parameter Value: It accepts one parameter, which is described below:
- attribute: This parameter specifies the model’s property.
Example 1: In this example, we are creating a model named orders and changing orderid. After that, we are applying the previous model to return the previous value.
HTML
<!DOCTYPE html>
<html>
<head>
<script src=
type="text/javascript">
</script>
<script src=
type="text/javascript">
</script>
<script src=
type="text/javascript">
</script>
</head>
<body>
<script type="text/javascript">
var orders = new Backbone.Model({
orderid: 180,
ordername: 'clothes',
address: 'guntur'
});
orders.set('orderid', 21);
document.write(JSON.stringify(orders.previous('orderid')));
</script>
</body>
</html>
|
Output:
180
Example 2: In this example, the item value is changed & accordingly displays both the values i.e. the last value & the changed value.
HTML
<!DOCTYPE html>
<html>
<head>
<script src=
type="text/javascript">
</script>
<script src=
type="text/javascript">
</script>
<script src=
type="text/javascript">
</script>
</head>
<body>
<script type="text/javascript">
var Fruit = new Backbone.Model({
item: "Grape",
taste: "sweet."
});
Fruit.set('item', 'GRAPES');
document.write("Item's value after set: ",
JSON.stringify(Fruit.changedAttributes()));
document.write("<br>");
document.write("Item's Last value: ",
Fruit.previous('item'));
</script>
</body>
</html>
|
Output:
Item's value after set: {"item":"GRAPES"}
Item's Last value: Grape
Reference: https://backbonejs.org/#Model-previous
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