JSFiddle - React, Tailwind, and code Playground

HTML

<body>

	
<div id="scoDom" class="score sc1">0</div>

<div id="scoExt" class="score sc2">
<label id="displayExt">0</label>
<div id=plusExt" class="addscoreExt">
	<a href="" onclick="incNumber();">
		<img src="images/challenge_score_addgoals.png">
	</a>
</div>

<div id=plusExt" class="removescoreExt">
	<a href="" onclick="decNumber();">
		<img src="images/change_score_removegoals.png">
	</a>
</div>
</div>


</body>
</html>

CSS

#scoDom
 {
    position: absolute;
    width: 100px;

        background-color: aliceblue;
}

#scoExt
 {
    position: absolute;
    width: 100px;
background-color: aliceblue;
}

.score.sc1 {
    border-radius: 5px 0 0 5px;
    top: 125px;
}

.addscoreExt {

  top: -60px;
    right: -27px;
    position: absolute;
}

.removescoreExt {

  top: 10px;
    right: -27px;
    position: absolute;
}

.score.sc2 {
    border-radius: 0 5px 5px 0;
    top: 125px;
    left: 110px;

}

.score {
    font-size: 6em;
    line-height: 1em;
    width: 105px;
    height: 97px;
    letter-spacing: -1px;
    color: cadetblue; /* changer si = 0 (blanc) pour betonscore ou rouge si perdu (résultat connu) */
    background: #fff;
    text-align: center;
    border: 0 none;
    font-family: fantasy;
    margin: 0;
    padding: 0;
    vertical-align: baseline;
}

JavaScript

var i = 0;

    function incNumber(i) {
        if (i < 10) {
            i++;
        } else if (i = 10) {
            i = 0;
        }
        document.getElementById("displayExt").innerHTML = i;
    }

    function decNumber(i) {
        if (i > 0) {
            --i;
        } else if (i = 0) {
            i = 10;
        }
        document.getElementById("displayExt").innerHTML = i;
    }