AngularJS binds data to HTML using Expressions.
AngularJS expressions can be written inside double braces: {{ expression }}.
AngularJS expressions can also be written inside a directive: ng-bind="expression".
AngularJS will resolve the expression, and return the result exactly where the expression is written.
AngularJS expressions are much like JavaScript expressions: They can contain literals, operators, and variables.
Example: {{ 5 + 5 }} or {{ firstName + " " + lastName }}
ng-app directive, HTML will display the expression as it is, without solving it:ng-app is an AngularJS directive. It's used to bootstrap (initialize) an AngularJS application within an HTML document.
When AngularJS loads, it looks for the ng-app directive to determine which part of the HTML document it should manage.
You can write expressions wherever you like. AngularJS will simply resolve the expression and return the result.
Example: Let AngularJS change the value of CSS properties.
Change the background color of the input box below:
AngularJS numbers are like JavaScript numbers:
AngularJS strings are like JavaScript strings: