Repeting a Math.random variable without getting the same result in three.js

Maybe a newbie question but i'd like to use a random variable several times in my code, but of course it reminds the same for all parameters using it. How could I fix it ?

Example :

var randomColor = [yellow, blue, green][Math.floor(Math.random() * 3)]

const cube1 = new THREE.Mesh(geometry, randomColor);
scene.add(cube1);

const cube2 = new THREE.Mesh(geometry, randomColor);
scene.add(cube2);

Those two cubes will have to same material (named randomColor) even if it is random. Thank you in advance !