Why XMLHttpRequest cannot load?

[wuxianliang]

When I open index.html in the demo directly, mistakes appear.

1. Failed to load resource: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'null' is therefore not allowed access. file:///Users/Liang/angular-isotope/demo/views/main.html

2. XMLHttpRequest cannot load file:///Users/Liang/angular-isotope/demo/views/main.html. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'null' is therefore not allowed access.

How to fix it?
Thank you very much.