as la funcion de un boton que calcule la masa masa quimica

Script
function calculateMolecularMass(elements){
    //elements is a list of elements
    //each element is a dictionary with the element name and number of atoms
    //example: [{"H":2}, {"O":1}]
    var mass = 0
    for (var i=0; i < elements.length; i++){
        var key = Object.keys(elements[i])[0]
        var value = elements[i][key]
        mass = mass + periodic_table[key] * value
    }
    return mass
}
    
calculateMolecularMass([{"H":2}, {"O":1}])