onload event not firing - JS

Question

Problem

So, my problem is that when I call my window.onload = app.setup, I want to append 0 to the elements with the classes of min and sec.

What I'm getting

<h1><span class="min"></span> : <span class="sec"></span></h1>

What I want

<h1><span class="min">0</span> : <span class="sec">0</span></h1>

// main class
class Main {
    constructor() {
        // stores time
        this.mins = 0;
        this.secs = 0;
        // stores users inputs
        this.workHours = null;
        this.restHours = null;
    }

    // sets up html    
    setup() {
        document.getElementsByClassName("min").innerHTML = toString(this.mins);
        document.getElementsByClassName("sec").innerHTML = toString(this.secs);
    }
}

let app = new Main();

window.onload = app.setup;

@import url('https://fonts.googleapis.com/css?family=Roboto:400,500');

* {
    margin: 0;
    padding: 0;
}

*::selection {
    background-color: #333;
    color: #fff;
}

.container {
    width: 60%;
    margin: 0 auto;
}

.clock {
    padding: 20px;
    text-align: center;
}

.clock h1 {
    color: #333;
    font: 500 1.8em Roboto;
}

.controls {
    text-align: center;
    padding: 20px;
}

.inputs input{
    width: 40%;
    margin: 10px;
    padding: 14px;
    border: none;
    outline: none;
    font: 400 1em Roboto;
    border-bottom: 3px solid #fff;
    transition: border-color 200ms ease-in-out;
    -webkit-transition: border-color 200ms ease-in-out;
    -o-transition: border-color 200ms ease-in-out;
    -moz-transition: border-color 200ms ease-in-out
}

.inputs input:focus {
    border-color: #333;
}

.buttons {
    padding: 10px;
}

.buttons button {
    padding: 15px;
    width: 20%;
    margin: 10px;
    border: none;
    outline: none;
    color: #fff;
    font: 500 1em Roboto;
    cursor: pointer
}

.buttons button:nth-child(1) {
    background-color: rgba(0, 0, 200, 0.6);
}

.buttons button:nth-child(2) {
    background-color: rgba(0, 200, 0, 0.6);
}

.buttons button:nth-child(3) {
    background-color: rgba(200, 0, 0, 0.6);
}

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Pomodoro Clock</title>
</head>
<body>
    <div class="container">

        <div class="clock">
            <h1><span class="min"></span> : <span class="sec"></span></h1>
        </div>

        <div class="controls">
            <div class="inputs">
                <input type="text" placeholder="Minutes of work">
                <input type="text" placeholder="Minutes of rest">
            </div>

            <div class="buttons">
                <button class="play"><i class="fa fa-play" aria-hidden="true"></i></button>
                <button class="pause"><i class="fa fa-pause" aria-hidden="true"></i></button>
                <button class="reset"><i class="fa fa-refresh" aria-hidden="true"></i></button>
            </div>
        </div>

    </div>

    <script src="https://use.fontawesome.com/e99695fe86.js"></script>
</body>
</html>

Ah I guess, because it is an event handler, `this` will refer to `window`. Otherwise it throw an error. In other words: When `app.setup` is called, `this` doesn't refer to `app`. — Felix Kling, Apr 19 '17 at 23:28
Related: [How to access the correct `this` inside a callback?](http://stackoverflow.com/q/20279484/218196) — Felix Kling, Apr 19 '17 at 23:30

score 1 · Accepted Answer · edited Apr 19 '17 at 23:31

1

document.getElementsByClassName returns a HTMLCollection (multiple elements) not just one element.

Try this:

setup() {
    document.getElementsByClassName("min")[0].innerHTML = this.mins.toString();
    document.getElementsByClassName("sec")[0].innerHTML = this.secs.toString();
}

Also, because you're trying to access properties of the Main class inside the setup function you'll have to bind the Main instance to the function.

window.onload = app.setup.bind(app);

edited Apr 19 '17 at 23:31

Felix Kling

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answered Apr 19 '17 at 23:24

Titus

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That's not the only problem (`app.setup` is not called properly). – Felix Kling Apr 19 '17 at 23:26
@FelixKling Why not ? – Titus Apr 19 '17 at 23:27
Because `this` will be `undefined` or `window` I guess. – Felix Kling Apr 19 '17 at 23:27
@SiddharthNand: Don't include solutions from answers in your question. It invalidates the answers. – Felix Kling Apr 19 '17 at 23:29
@FelixKling You're right, he is accessing `this.mins` and `this.secs` inside the `setup` function. – Titus Apr 19 '17 at 23:30

onload event not firing - JS

1 Answers1