diff --git a/tienda_ilusion/don_confiao/static/js/sale_summary.js b/tienda_ilusion/don_confiao/static/js/sale_summary.js
index 49ffe1b..5545163 100644
--- a/tienda_ilusion/don_confiao/static/js/sale_summary.js
+++ b/tienda_ilusion/don_confiao/static/js/sale_summary.js
@@ -3,12 +3,16 @@ const quantityLines = document.getElementById('id_quantity_lines');
 const quantityProducts = document.getElementById('id_quantity_products');
 const ammountInput = document.getElementById('id_ammount');
 const idPrefix = 'id_saleline_set-';
+const quantitySuffix = '-quantity';
+const priceSuffix = '-unit_price';
+const quantityRegexSelector = `[id^="${idPrefix}"][id$="${quantitySuffix}"]`;
+const priceRegexSelector = `[id^="${idPrefix}"][id$="${priceSuffix}"]`;
 
 complete_form.addEventListener('change', function(event){
-    if (event.target.matches('[id^="${idPrefix}"][id$="-quantity"]')) {
+    if (event.target.matches(quantityRegexSelector)) {
         calculateSummary();
     }
-    if (event.target.matches('[id^="id_saleline_set-"][id$="-unit_price"]')) {
+    if (event.target.matches(priceRegexSelector)) {
         calculateSummary();
     }
 });
@@ -17,13 +21,13 @@ complete_form.addEventListener('change', function(event){
 function calculateSummary() {
     let quantity = 0;
     let ammount = 0;
-    const quantityInputs = document.querySelectorAll('[id^="id_saleline_set-"][id$="-quantity"]');
+    const quantityInputs = document.querySelectorAll(quantityRegexSelector);
     const ids = Array.prototype.map.call(quantityInputs, function(input) {
         return input.id.match(/\d+/)[0];
     });
     ids.forEach(function(id) {
-        let lineQuantity = document.getElementById(`id_saleline_set-${id}-quantity`)
-        let linePrice = document.getElementById(`id_saleline_set-${id}-unit_price`)
+        let lineQuantity = document.getElementById(`${idPrefix}${id}${quantitySuffix}`)
+        let linePrice = document.getElementById(`${idPrefix}${id}${priceSuffix}`)
         quantity += parseFloat(lineQuantity.value);
         ammount += parseFloat(linePrice.value) * parseFloat(lineQuantity.value);
     });