js获取页面的变量的值吗

var globalVar = "I am a global variable";
console.log(globalVar); // 输出: I am a global variable

function getLocalVar() {
    var localVar = "I am a local variable";
    return localVar;
}
console.log(getLocalVar()); // 输出: I am a local variable

<input type="text" id="myInput">
<script>
    var inputValue = document.getElementById('myInput').value;
    console.log(inputValue);
</script>

<p id="myParagraph">Hello World!</p>
<script>
    var paragraphText = document.getElementById('myParagraph').innerText;
    console.log(paragraphText); // 输出: Hello World!
</script>

window.onload = function() {
    var element = document.getElementById('someElement');
    if (element) {
        console.log(element.value);
    }
};