forminatorConditionalCalculation.php

<?php
/* Inline script printed out in the footer */
add_action('wp_footer', 'forminator_conditional_calculation_script_wp_footer');
function forminator_conditional_calculation_script_wp_footer() {
    ?>
        <script>
	//Demo -> https://cuban.tempurl.host/forminator-if-conditional/
	//Checking if the forminator form [forminator_form id="1046668"] exist on the page 
	if(jQuery("#forminator-module-1046668")){
		/* In this example the calculation is {hidden-1}*{number-1}*{number-2} */
		/*Use HTML field to show the Price Value({hidden-1}) */
		//It need the field subject to the conditions be part of the form in this case {hidden-1}
		//This field need to be hidden
		var priceField = jQuery("#hidden-1");
		//A variable to hold the original price value, 
		var frmPrice = 15; //Need to be here to avoid cache/cookies issues
		//The field that trigger the condition (Usually the same on the condition, but you can use as many you wich)
		var totalPersonField = jQuery("#forminator-field-number-1");

		//For every field involded on the conditional need to trigger the onChange event with the custom function applyDiscount 
		totalPersonField.change(applyDiscountForm1046668);

		//applyDiscount is the logic of the conditional
		function applyDiscountForm1046668(){
			//Local variable to get the value of the field in the condition, create as many field involved
			let total_person = totalPersonField.val();
			//Conditions to apply the discount
			//Javascript If/Else ---> https://www.w3schools.com/js/js_if_else.asp
			//Javascript Comparisson ---> https://www.w3schools.com/js/js_comparisons.asp
			if(total_person >= 2 && total_person <= 9){
				//If the total of persons is > 1 will apply a 10% discount, simpele way to do it price*90/100 = price*0.9
				priceField.val(frmPrice*0.9);
			}
			else if(total_person >= 10 && total_person <= 15){
				//20% discount
				priceField.val(frmPrice*0.8);
			}
			else if(total_person >= 16 && total_person <= 20){
				//30% discount
				priceField.val(frmPrice*0.7);
			}
			else if(total_person >= 21 && total_person <= 39){
				//40% discount
				priceField.val(frmPrice*0.6);
			}		
			else if(total_person >= 40){
				//50% discount
				priceField.val(frmPrice*0.5);

			}
			else{
			        //If none of the condition apply use the original price set on the form
				priceField.val(frmPrice);
			}
		}
	}
    </script>
    <?php
}