When writing JSX, it’s common to use variables to set attributes.

Here’s an example of how that might work:

// Use a variable to set the `height` and `width` attributes:

const sideLength = "200px";

const panda = (
  <img 
    src="images/panda.jpg" 
    alt="panda" 
    height={sideLength} 
    width={sideLength} />
);

Notice how in this example, the <img />‘s attributes each get their own line. This can make your code more readable if you have a lot of attributes on one element.

Object properties are also often used to set attributes:

const pics = {
  panda: "http://bit.ly/1Tqltv5",
  owl: "http://bit.ly/1XGtkM3",
  owlCat: "http://bit.ly/1Upbczi"
}; 

const panda = (
  <img 
    src={pics.panda} 
    alt="Lazy Panda" />
);

const owl = (
  <img 
    src={pics.owl} 
    alt="Unimpressed Owl" />
);

const owlCat = (
  <img 
    src={pics.owlCat} 
    alt="Ghastly Abomination" />
);