我可以对else语句使用两个动作吗？

Question

Sorry if it's a basic question but i can't make two "actions" work on one single else if.

I want it to say different greetings and at the same time change the background color of body based on the present hour.

The code works without this line:

document.getElementById("####").style.background = '#######';

This is the code that doesn't work:

    var today = new Date();
    var hourNow = today.getHours();
    var greeting;

    if (hourNow > 20) {
        greeting = 'Boa noite!'; document.getElementById("body").style.background = '#000000';
    } else if (hourNow > 12) {
        greeting = 'Boa tarde!';
        document.getElementById("body").style.background = '#ffffff'; 
    } else if (hourNow > 0) {
        greeting = 'Bom descanço!'; document.getElementById("body").style.background = '#121212';
    } else if (hourNow > 7) {
        greeting = 'Bom dia!'; document.getElementById("body").style.background = '#bf3d3d';
    }
    document.write(greeting);

I appreciate every help i can get! Thank you in advanced!!

Answer 1

You could use an object for the wanted parameters to change and use an array of the keys in the wanted order with a callback for changing the given values.

 var greetings = { 20: { greeting: 'Boa noite!', background: '#000000' }, 12: { greeting: 'Boa tarde!', background: '#ffffff' }, 7: { greeting: 'Bom dia!', background:'#bf3d3d' }, 0: { greeting: 'Bom descanço!', background: '#121212' } }, hourNow = (new Date).getHours(); [20, 12, 7, 0].some(function (hour) { if (hourNow >= hour) { // check for greater and equal document.getElementById("greeting").innerHTML = greetings[hour].greeting; document.body.style.background = greetings[hour].background; return true; // exit loop } }); 

 <div id="greeting" style="background-color: #ffffff;"></div> 

Answer 2

You should add an <h1> tag to your body and then set the innerText on that for the greeting.

<!-- HTML -->
<h1 id="greeting"></h1>

// JS
var greeting = document.getElementById('greeting');

if (hourNow > 20) {
    greeting.innerText = 'Boa noite!';
    document.body.style.backgroundColor = '#000000';
}

Answer 3

You should put

else if (hourNow > 7)

before

else if (hourNow > 0)

Right now the last else if is unreachable

Answer 4

当您不提供case的break ，可以使用switch语句并利用掉线行为。