JSFiddle - React, Tailwind, and code Playground

HTML

<select id="language">
    <option value="en" >English</option>
    <option value="zh" >Chinese</option>
    <option value="it" >Italian</option>
    <option value="fr" >French</option>
    <option value="ja" >Japanese</option>
    <option value="es" >Spanish</option>
</select>
<div id="welcome"></div>
<div id="test"></div>

JavaScript

var translations = 
{ 
    "en" : { 
        "SomeText" : "Test in English",
        "Welcome" : "Welcome in English"
    },
    "zh" : { 
        "SomeText" : "Test in Chinese",
        "Welcome" : "Welcome in Chinese"
    },
    "it" : { 
        "SomeText" : "Test in Italian",
        "Welcome" : "Welcome in Italian"
    },
    "fr" : { 
        "SomeText" : "Test in French",
        "Welcome" : "Welcome in French"
    },
    "ja" : { 
        "SomeText" : "Test in Japanese",
        "Welcome" : "Welcome in Japanese"
    },
    "es" : { 
        "SomeText" : "Test in Spanish",
        "Welcome" : "Welcome in Spanish"
    }
};

var language = "en";

function writeInLanguage(){
    $("#welcome").text(translations[language].Welcome);
    $("#test").text(translations[language].SomeText);
    console.log($("#language").val());
}

$("#language").on("change", function(){
    language = $("#language").val();
    writeInLanguage();
});
writeInLanguage();