I just started full stack development and I'm currently working with node, js and django. On my home page I have 2 products(express) but when I click on an individual product I get redirected to a blank page and I'm not sure why

Here is my code for individual product

window.onload = ()=>{
    let params = window.location.search;
  let urlParams = new URLSearchParams(params);
  let productID = urlParams.get("id");
  // http://127.0.0.1:8000/api/products/id 
  if(productID != null && typeof(productID)!= 'undefined'){
      fetch('http://127.0.0.1:8000/api/products/'+productID)
      .then(resp => resp.json())
      .then(data => {
          console.log(data);
          if('detail' in data){
              // display some generic product not found error
          }
          else{
              let name = data['name'];
              let desc = data['description'];
              let price = data['price'];
              let image= data['image'];
                            // display the product data 
                            
          }
      });
  }
}