написал fetch для search

assets/css/gp-style-desktop.css

@@ -269,6 +269,11 @@
 
     background-color: var(--background-grey-hover);
     border-radius: 4px;
+
+    display: none;
+}
+.header-menu-search__found.active{
+    display: block;
 }
 .header-menu-search__error{}
 .header-menu-search__item{

assets/js/main.js

@@ -260,6 +260,92 @@ btnOpenSearchPhone.onclick = function () {
     searchPhone.classList.toggle('active');
 }
 
+// pc
+let inputSearchPc = document.querySelector('.header-menu-search__input'),
+    btnSearchPc = document.querySelector('.header-menu-search__btn');
+
+btnSearchPc.onclick = function () {
+    let value = inputSearchPc.value,
+        newPost = {
+            value: value,
+        };
+
+    postSearch(newPost, 'pc');
+}
+
+// phone
+let inputSearchPhone = document.querySelector('.phone-search__input');
+
+inputSearchPhone.addEventListener('input', function(event) {
+    let value = event.target.value,
+        newPost = {
+            value: value,
+        };
+
+    postSearch(newPost, 'phone');
+});
+
+function postSearch(newPost, device) {
+    let contentPc = document.querySelector('.header-menu-search__found'),
+        contentPhone = document.querySelector('.phone-search__found');
+
+    fetch('http://jsonplaceholder.typicode.com/posts', {
+        method: 'POST',
+        // body: JSON.stringify(newPost),
+        headers: {
+          'Content-type': 'application/json; charset=UTF-8',
+        },
+      })
+        .then((data) => {
+            if (device == 'pc') {
+                contentPc.innerHTML = '';
+
+                contentPc.innerHTML = `<div class="header-menu-search__item">
+                                    <img src="assets/img/photo/header-menu-search.png" alt="" class="header-menu-search-item__img">
+
+                                    <div class="header-menu-search-item__content">
+                                        <p class="text-2">Беговая дорожка механическая DRAXFIT+</p>
+                                        <p class="header-menu-search-item__art text-2">Артикул:&nbsp;STP1000C</p>
+                                    </div>
+                                </div>`;
+
+                contentPc.classList.add('active');
+            }else{
+                contentPhone.innerHTML = '';
+
+                contentPhone.innerHTML = `<div class="phone-search__item">
+                            <img src="assets/img/photo/header-menu-search.png" alt="" class="phone-search-item__img">
+                        
+                            <div class="phone-search-item__content">
+                                <p class="text-2">Беговая дорожка механическая DRAXFIT+</p>
+                                <p class="phone-search-item__art text-2">Артикул:&nbsp;STP1000C</p>
+                            </div>
+                        </div>`;
+
+                contentPhone.classList.add('active');
+            }
+        }).catch(
+            () => {
+              if (device == 'pc') {
+                postError(contentPc);
+              }else{
+                postError(contentPhone);
+              }
+            }
+        )
+}
+
+function postError(divContent) {
+    divContent.innerHTML = ''
+                
+    let p = document.createElement("p");
+    p.textContent = "Произошла ошибка"
+    p.className = "header-menu-search__error text-2";
+
+    divContent.appendChild(p);
+}
+
+
 // search end
 
 // open-modal

index.html

@@ -228,7 +228,7 @@
                             <input type="text" class="header-menu-search__input" placeholder="Поиск">
 
                             <div class="header-menu-search__found">
-                                <div class="header-menu-search__item">
+                                <!-- <div class="header-menu-search__item">
                                     <img src="assets/img/photo/header-menu-search.png" alt="" class="header-menu-search-item__img">
 
                                     <div class="header-menu-search-item__content">
@@ -244,7 +244,7 @@
                                         <p class="text-2">Беговая дорожка механическая DRAXFIT+</p>
                                         <p class="header-menu-search-item__art text-2">Артикул: STP1000C</p>
                                     </div>
-                                </div>
+                                </div> -->
 
                                 <!-- <p class="header-menu-search__error text-2">
                                     К сожалению, по вашему запросу ничего не найдено
@@ -356,19 +356,19 @@
                 <div class="phone-search__content">
                     <input type="text" class="phone-search__input" placeholder="Поиск">
 
-                    <div class="phone-search__found active">
+                    <div class="phone-search__found">
                         <!-- <p class="text-1">
                             К сожалению, по вашему запросу ничего не найдено
                         </p> -->
 
-                        <div class="phone-search__item">
+                        <!-- <div class="phone-search__item">
                             <img src="assets/img/photo/header-menu-search.png" alt="" class="phone-search-item__img">
                         
                             <div class="phone-search-item__content">
                                 <p class="text-2">Беговая дорожка механическая DRAXFIT+</p>
                                 <p class="phone-search-item__art text-2">Артикул:&nbsp;STP1000C</p>
                             </div>
-                        </div>
+                        </div> -->
                     </div>
                 </div>
             </div>