JavaScript 不会向页面打印任何内容

Question

After running the HTML file the page appears blank.

 var person = { firstName: "John", lastName: "Doe", age: 50, eyeColor: "blue" }; function myFunction() { document.getElementById("demo").innerHTML = person.firstName + " " + person.lastName; }

 <p id="demo"></p>

What might be wrong?

Answer 1

• A better approach, when the DOM is fully loaded using the event DOMContentLoaded .

 var person = { firstName: "John", lastName: "Doe", age: 50, eyeColor: "blue" }; function myFunction() { document.getElementById("demo").innerHTML = person.firstName + " " + person.lastName; } document.addEventListener("DOMContentLoaded", function(event) { console.log("DOM fully loaded and parsed"); myFunction(); });

 <p id="demo"></p>

Answer 2

To clarify what @tkausl said in the comment, you have defined a function, but have yet to execute (called) it. Try doing this:

 var person = { firstName: "John", lastName: "Doe", age: 50, eyeColor: "blue" }; function myFunction() { document.getElementById("demo").innerHTML = person.firstName + " " + person.lastName; } myFunction();

 <p id="demo"></p>

Answer 3

You need to call the function somewhere in the js code.. Something like:

window.onload="myFunction()";

Or, make it a self executing function:

<script>
(function() {
    myFunction()
})();
</script>