Angular.js Filters

In Angular.js, filters are used to format and transform data displayed in the UI. They provide a way to apply formatting rules to expressions in templates.

1. Overview

Angular.js filters allow you to:

Format Data: Filters can be used to format data before displaying it in the view. For example, you can format dates, numbers, or currency values according to specific rules.
Transform Data: Filters can transform data in various ways, such as converting text to uppercase or lowercase, filtering arrays based on specific criteria, or sorting arrays.
Chain Filters: Multiple filters can be chained together to apply multiple transformations to data. Filters are applied in left-to-right order.

2. Usage

To use filters in Angular.js, you apply them to expressions in templates using the pipe (|) syntax:

<div>
    <!-- Apply filters to data -->
    {{ data | filter1 | filter2 | ... }}
</div>

Filters can be used with various Angular.js directives, such as ng-repeat or ng-bind, to format or transform data.

3. Built-in Filters

Angular.js provides several built-in filters for common formatting and transformation tasks:

currency: Formats a number as currency.
date: Formats a date object.
filter: Filters an array based on a predicate function or string.
json: Formats an object as JSON string.
limitTo: Limits the number of items displayed in an array or string.
lowercase: Converts a string to lowercase.
uppercase: Converts a string to uppercase.

4. Custom Filters

In addition to built-in filters, you can create custom filters in Angular.js to perform specific formatting or transformation tasks. Custom filters are defined as Angular.js filter functions and registered with the module.

// Define a custom filter function
app.filter('customFilter', function() {
    return function(input) {
        // Filter logic
        return transformedOutput;
    };
});

Once defined, custom filters can be applied to expressions in templates like built-in filters.

5. Conclusion

Angular.js filters provide a powerful way to format and transform data in Angular.js applications. By applying built-in or custom filters to expressions in templates, you can easily manipulate data to meet specific requirements.

Archive