JavaScript Variables

Variables are containers for storing data values. In this example, x, y, and z, are variables, declared with the var keyword:

var x = 5;
var y = 6;
var z = x + y;

When to Use var, let, or const?

1. Always declare variables
2. Use const if the value should not be changed
3. Use const if the type should not be changed (Arrays and Objects)
4. Only use let if you can't use const
5. Only use var if you MUST support old browsers.