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Render value without data-binding

In AngularJS, how can I render a value without 2-way data binding? One may want to do this for performance reasons, or even rendering a value at a given point in time.

The following examples both use data binding:

<div>{{value}}</div>

<div data-ng-bind="value"></div>

How do I render value without any data binding?

like image 480
Blowsie Avatar asked Sep 13 '13 15:09

Blowsie


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3 Answers

Angular 1.3+

In 1.3, Angular has supported this using the following syntax.

<div>{{::message}}</div>

As mentioned in this answer.


Angular 1.2 and below

This is simple and doesn't need a plugin. Check this out.

This small directive will easily accomplish what you are trying to achieve

app.directive('bindOnce', function() {
    return {
        scope: true,
        link: function( $scope ) {
            setTimeout(function() {
                $scope.$destroy();
            }, 0);
        }
    }
});

You can bind once like this

<div bind-once>I bind once - {{message}}</div>

You can bind like normal

<div ng-bind="message" bind-once></div>

Demo: http://jsfiddle.net/fffnb/

Some of you may be using angular batarang, and as mentioned in the comments if you use this directive the element still shows as binding when it is not, I am pretty sure this has something to do with the classes that are attached to the element so try this, it should work (not tested). Let me know in the comments if it worked for you.

app.directive('bindOnce', function() {
    return {
        scope: true,
        link: function( $scope, $element ) {
            setTimeout(function() {
                $scope.$destroy();
                $element.removeClass('ng-binding ng-scope');
            }, 0);
        }
    }
});

@x0b: If you have OCD and you want to remove the empty class attribute do this

!$element.attr('class') && $element.removeAttr('class')
like image 171
iConnor Avatar answered Oct 19 '22 12:10

iConnor


It looks like Angular 1.3 (starting with beta 10) has one-time binding built in:

https://docs.angularjs.org/guide/expression#one-time-binding

One-time binding

An expression that starts with :: is considered a one-time expression. One-time expressions will stop recalculating once they are stable, which happens after the first digest if the expression result is a non-undefined value (see value stabilization algorithm below).

like image 49
Karen Zilles Avatar answered Oct 19 '22 11:10

Karen Zilles


Use the bindonce module. You'll need to include the JS file and add it as a dependency to your app module:

var myApp = angular.module("myApp", ['pasvaz.bindonce']);

This library allows you to render items that are bound only once — when they are first initialized. Any further updates to those values will be ignored. It's a great way to reduce the number of watches on the page for things that won't change after they are rendered.

Usage example:

<div bo-text="value"></div>

When used like this, the property under value will be set once it is available, but then the watch will be disabled.

like image 20
OverZealous Avatar answered Oct 19 '22 11:10

OverZealous