JSFiddle - React, Tailwind, and code Playground

HTML

<textarea id="my-input"></textarea>

JavaScript

$(document).ready(function() {
    $('#my-input').on('input', function() {
        var $input = $(this),
            curVal = $input.val();
        var cursorPos = curVal.slice(0, this.selectionStart).length;
        
        $input.val(curVal.replace(/[|]/g, '।'));
        this.setSelectionRange(cursorPos, cursorPos);
    });
});