JSFiddle - React, Tailwind, and code Playground

HTML

<table  border="1" id="table">
<colgroup>
<col width="100"/>
<col width="100"/>
</colgroup>
<tr>
<td style="text-align:center;">Activity</td>
<td style="text-align:center;">Time</td>
</tr>
<tr>
<td style="text-align:center;">
<select id="activity[]">
<option value="Working">Working</option>
<option value="Leave">Leave</option>
</select>
</td>
<td style="text-align:center;"><input style="width:35px;" type="text" class="text" maxlength="3" id="day1[]"/></td>
</tr>
</table>
<br><br>
<input type="button" value="+" id="plus" />

JavaScript

$("#plus").click(function(e){

		$("#table").append("<tr><td style='text-align:center;'><select id='activity[]'><option value='Working'>Working</option><option value='Leave'>Leave</option></select></td><td style='text-align:center;'><input style='width:35px;' type='text' class='text' maxlength='3' name='day1' id='day1[]'/></td></tr>");
		e.preventDefault();
		

	});



 		$.each($('[id^=day1]'), function (i, item) {
                 $("[id*='day1']").keyup(function () {
                 if (this.value.match(/[^a-zA-Z.]/g)) {
                    this.value = this.value.replace(/[^a-zA-Z.]/g, '');
                    
                }
            	});

            	});