I have the following list of objects:

[
    { "name" : "foo", "description" : "description of foo..." },
    { "name" : "bar", "description" : "description of bar..." },
    { "name" : "baz" },
    ...
]

All objects have a name, but some have an associated description, and the rest do not.

I use the following template with an input field connected to a typeahead, to show each matching object:

<script type="text/ng-template" id="my-template.html">
    <a style="text-align: left;">
        <span style="font-size: 18px; display:block;">{{match.model.name}}</span> 
        <span ng-show="typeof({{match.model.description}}) !== 'undefined'">{{match.model.description}}</span>
    </a>
</script>

I would like the template to show the description only when its value is defined, but my use of ng-show returns parsing errors.

How should I use ng-show or another directive to render the description, only when this object key (and its value) is available?

I have the following list of objects:

[
    { "name" : "foo", "description" : "description of foo..." },
    { "name" : "bar", "description" : "description of bar..." },
    { "name" : "baz" },
    ...
]

All objects have a name, but some have an associated description, and the rest do not.

I use the following template with an input field connected to a typeahead, to show each matching object:

<script type="text/ng-template" id="my-template.html">
    <a style="text-align: left;">
        <span style="font-size: 18px; display:block;">{{match.model.name}}</span> 
        <span ng-show="typeof({{match.model.description}}) !== 'undefined'">{{match.model.description}}</span>
    </a>
</script>

I would like the template to show the description only when its value is defined, but my use of ng-show returns parsing errors.

How should I use ng-show or another directive to render the description, only when this object key (and its value) is available?

• javascript
• angularjs

Share Improve this question Follow asked Mar 3, 2016 at 21:17 Alex ReynoldsAlex Reynolds 97.1k5959 gold badges250250 silver badges351351 bronze badges

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4 Answers 4

Sorted by: Reset to default 3

You should only check for variable value, that's enough

<span ng-if="match.model.description">{{match.model.description}}</span>

<script type="text/ng-template" id="my-template.html">
    <a style="text-align: left;">
        <span style="font-size: 18px; display:block;">{{match.model.name}}</span> 
        <span ng-show="match.model.description">{{match.model.description}}</span>
    </a>
</script>

Just use it without typeof - and don't use the curly brackets, as ng-show is already relative to your scope. In JavaScript, if(undefined) has the same oute as if(false) (see Undefined variables, value == false versus !value)

<script type="text/ng-template" id="my-template.html">
  <a style="text-align: left;">
    <span style="font-size: 18px; display:block;">{{match.model.name}}</span> 
    <span ng-show="match.model.description">{{match.model.description}} </span>
  </a>
</script>

use ng-if="match.model.description" instead of ng-show. ngIf differs from ngShow in that ngIf pletely removes and recreates the element in the DOM rather than changing its visibility via the display css property.