JSFiddle - React, Tailwind, and code Playground

JavaScript

var originalXValue = 'ekis';
var originalYValue = 'igriega';
var x = 'ekis';
var y = 'igriega';

function pollute()
{
    // Uncomment one of the following lines to see any pollution.
    // x = 'ex'; y = 'why';      // both polluted
    // var x = 'ex'; y = 'why';  // y was polluted
    // var x = y = 'shared-ex';  // y was polluted  
    var x = 'oneline', y = x;      // No pollution
    // var x = 'ex', y = 'ex';   // No pollution
      
    document.write('Pollution function running with variables<br/>' +
                   'x: ' + x + '<br/>y: ' + y + '<br/><br/>');
}

pollute();

if (x !== originalXValue && y !== originalYValue)
{
    document.write('both polluted');
}
else if (x !== originalXValue)
{
    document.write('x was polluted');
}
else if (y !== originalYValue)
{
    document.write('y was polluted');
}
else
{
    document.write('No pollution');
}