Snippet to add a custom attribute to each vertex of buffergeometry in three.js

customAttributes.js

    // Snippet to look under a buffergeometry and add a custom attribute for each vertex
    let geometry = new THREE.PlaneBufferGeometry(5, 5, 5, 5);  // for example
    
    let count = geometry.attributes.position.length;
    let arrSize = new THREE.BufferAttribute(new Float32Array(count), 1);  // Here "1" is the places the attribute would take
    for(let i=0;i<arrSize.count; i++){
      arrSize.array[i] = Math.random(); // Assigning a random value as attribute here
    }
    geometry.addAttribute("aSize", arrSize, 1); // Access in shader later