var C1 = 1;
var C2 = 2;
const C3 = 3;

function f(x) {
    var s = "";

    switch(x) {
    case C1:
        s += "1";
    case C2:
        s += "2";
        break;
    case C3:
        s += "3";
    default:
        s += "d";
    case 4:
        s += "4";
    }
    return s;
}
assertEq(f(1), "12");
assertEq(f(2), "2");
assertEq(f(3), "3d4");
assertEq(f(4), "4");

assertEq(f(0), "d4");
assertEq(f(-0), "d4");

assertEq(f(true), "d4");