React 4 - conditions rendering

• 　　if conditions or operator to create an element

 

• Variable elements

 

 

• The AND operator &&

 

 

JavaScript, true && expression always will return  expression, and  false && expression will always return  false.

Therefore, if the conditions  true, && the elements on the right side will be rendered, if it is  false, React ignore and skip it.

 

•  Ternary operator

 

 

 

• Prevent component rendering

 

In the component of  render the return process  null and will not affect the life cycle of components. For example, the above example, componentDidUpdate will still be called