Development mode in salesforce enables developers to embed visualForce page editor in the browser. Enabling Development mode in Salesforce is very essential for developers to build visualforce pages in the view state.
After enabling we can see both code and preview of the visualforce page in the same window.
How to Enable Development mode in Salesforce
Salesforce development mode can be enabled, Navigate to Name | Personal Advanced User.
In advance user details, we can edit assignments, can create new group's, Create new Queue, and can access Salesforce Login History details like Login Time, Source IP, Login Type, Login URL, Location.
To Enable salesforce development mode click on Edit button.
Now go to User details section and Enable Development Mode check Box.
Click on Save Button.
How to check Salesforce Development Mode Enabled or Not
To check development mode in salesforce, Navigate to Setup | Build | Visualforce Pages.
Now Create a new Visualforce page and Quick save the page.
Now click on preview button and the result will be opened in new window.
Click and drag the button. Now visualforce page code and result will be displayed.
What is View State in Salesforce
ViewState in salesforce holds the stage of the Visualforce page which includes components, field values and controller state.
Salesforce developer environment has a view state inspector, which let user to view the content of the view state.
Performance of the page depends efficiently managing the view state.