AngularJS Expressions

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AngularJS usesexpressionto bind data to HTML.

AngularJS Expressions

AngularJS expressions can be written within double curly braces:{{ expression }}.

AngularJS expressions can also be written within directives:ng-bind="expression".

AngularJS will parse the expression and return the result at the location where the expression is written.

AngularJS Expressionsare very similar to JavaScript expressions: They can contain literals, operators, and variables.

Example {{ 5 + 5 }} or {{ firstName + " " + lastName }}

Example

<!DOCTYPE html>
<html>
<script src="https://cdn.staticfile.net/angular.js/1.6.9/angular.min.js"></script>
<body>
<div ng-app="">
  <p>My first expression: {{ 5 + 5 }}</p>
</div>
</body>
</html>

Try it yourself

If you remove ng-app Directives, HTML will display expressions as is without parsing them:

Example

<!DOCTYPE html>
<html>
<script src="https://cdn.staticfile.net/angular.js/1.6.9/angular.min.js"></script>
<body>
<div>
  <p>My first expression: {{ 5 + 5 }}</p>
</div>
</body>
</html>

Try it yourself

You can write expressions at any location you like, and AngularJS will simply parse the expression and return the result.

Example: Let AngularJS change the value of a CSS property.

Change the color of the following input box by changing its value:

Light blue

Example

<div ng-app="" ng-init="myCol='lightblue'">
<input style="background-color:{{myCol}}" ng-model="myCol">
</div>

Try it yourself

AngularJS Numbers

AngularJS numbers are similar to JavaScript numbers:

Example

<div ng-app="" ng-init="quantity=1;cost=5">
<p>Total amount (USD): {{ quantity * cost }}</p>
</div>

Try it yourself

Using ng-bind Same example:

Example

<div ng-app="" ng-init="quantity=1;cost=5">
<p>Total amount (USD): <span ng-bind="quantity * cost"></span></p>
</div>

Try it yourself

Using ng-init is not common. You will learn better methods for initializing data in the chapter about controllers.

AngularJS Strings

AngularJS strings are similar to JavaScript strings:

Example

<div ng-app="" ng-init="firstName='Bill';lastName='Gates'">
<p>Name is {{ firstName + " " + lastName }}</p>
</div>

Try it yourself

Same example using ng-bind:

Example

<div ng-app="" ng-init="firstName='Bill';lastName='Gates'">
<p>Name is <span ng-bind="firstName + ' ' + lastName"></span></p>
</div>

Try it yourself

AngularJS Objects

AngularJS objects are similar to JavaScript objects:

Example

<div ng-app="" ng-init="person={firstName:'Bill',lastName:'Gates'}">
<p>Name is {{ person.lastName }}</p>
</div>

Try it yourself

Same example using ng-bind:

Example

<div ng-app="" ng-init="person={firstName:'Bill',lastName:'Gates'}">
<p>Name is <span ng-bind="person.lastName"></span></p>
</div>

Try it yourself

AngularJS Arrays

AngularJS arrays are similar to JavaScript arrays:

Example

<div ng-app="" ng-init="points=[1,15,19,2,40]">
<p>The third result is {{ points[2] }}</p>
</div>

Try it yourself

Same example using ng-bind:

Example

<div ng-app="" ng-init="points=[1,15,19,2,40]">
<p>The third result is <span ng-bind="points[2]"></span></p>
</div>

Try it yourself