如何为复选框定义变量，并使用该变量查找选中或未选中的值？

<input type="checkbox" id="checkbox1" value="value1"> Option 1
<input type="checkbox" id="checkbox2" value="value2"> Option 2
<input type="checkbox" id="checkbox3" value="value3"> Option 3

var checkbox1 = document.getElementById("checkbox1");
var checkbox2 = document.getElementById("checkbox2");
var checkbox3 = document.getElementById("checkbox3");

if (checkbox1.checked) {
    console.log("Option 1 is selected");
} else {
    console.log("Option 1 is not selected");
}

if (checkbox2.checked) {
    console.log("Option 2 is selected");
} else {
    console.log("Option 2 is not selected");
}

if (checkbox3.checked) {
    console.log("Option 3 is selected");
} else {
    console.log("Option 3 is not selected");
}

app.post("/submit", function(req, res) {
    var checkboxValue = req.body.checkboxName;
    if (checkboxValue === "value1") {
        console.log("Option 1 is selected");
    } else {
        console.log("Option 1 is not selected");
    }
});