What do curly braces mean in JSX (React)?

Question

For an example, to set a style in react you could do

var css = {color: red}

and

Hello world

Answer 1

You put curly braces when you want to use the value of a variable inside "html" (so inside the render part). It's just a way of telling the app to take the value of the variable and put it there, as opposed to a word.