Redirect all pages to Index.html using htaccess file

Open .htaccess file in your domain root folder. and put in the following code:
 

RewriteEngine on
RewriteCond %{REQUEST_URI} !^/index.html$
RewriteRule .* /index.html [L,R=302]

 The following will exclude redirection of image files :

RewriteEngine on
RewriteCond %{REQUEST_URI} !^/index.html$
RewriteCond %{REQUEST_URI}!(gif|jpe?g|png|css|js)$
RewriteRule .* /index.html [L,R=302]