JSFiddle - React, Tailwind, and code Playground

HTML

<head>
<script>
function surligne(champ, erreur){
   if(erreur)
      champ.style.backgroundColor = "#fba";
   else
      champ.style.backgroundColor = "#fff";
	}
 
function VerifPrix(champ){
   var Prix = parseInt(champ.value);
   if(isNaN(Prix) ||  Prix < 0){
      surligne(champ, true);
      return true;
	  }
   else {
      surligne(champ, false);
      return false;
	  }
}
</script>
</head>
 
<body>
<input type="text" id="PtEntre_1" name="PtEntre_1" value="" size="5" onkeyup="Chargement_Pos1()" onblur="VerifPrix(this)"/>
<br>
<input type="text" id="Strike_1" name="Strike_1" value="" size="6" onblur="VerifPrix(this)"/>
</body>