My JS console says that .getTime is not a function when i use the getTime() method in JS

I am not able to use the .getTime() method, can someone help me? Error message in link! The original date is just from basic html date input.

JS:

document.getElementById("lastMenDate").addEventListener("change", function () {
    var inputMen = this.value;
    var lastMenDate = new Date(inputMen);
    console.log(lastMenDate);
});

document.getElementById("targetDate").addEventListener("change", function () {
    var inputTar = this.value;
    var targetDate = new Date(inputTar);
    console.log(targetDate);
});

document.getElementById("calc").addEventListener("click", function () {
    var timeDifference = targetDate.getTime() - lastMenDate.getTime();
    var daysDifference = timeDifference / (1000 * 24 * 60 * 60);
    console.log(daysDifference);
});

error

as commented, your vars are not scoped to the window / "all functions", so you can just assign your variable to the window/global and reference it that way. You could also look at creating an object which employs the calculation.

document.getElementById("lastMenDate").addEventListener("change", function () {
    var inputMen = window.inputMen = this.value;
    var lastMenDate = window.lastMenDate = new Date(inputMen);
    console.log(lastMenDate);
});

document.getElementById("targetDate").addEventListener("change", function () {
    var inputTar = window.inputTar = this.value;
    var targetDate = window.targetDate = new Date(inputTar);
    console.log(targetDate);
});

document.getElementById("calc").addEventListener("click", function () {
    var timeDifference = window.timeDifference = window.targetDate.getTime() - window.lastMenDate.getTime();
    var daysDifference = window.daysDifference = timeDifference / (1000 * 24 * 60 * 60);
    console.log(daysDifference);
});