Same addition of array objects

 let obj = {
    
    };
 const arr = [
 {
    
     name: 'A', stock: 1 }, 
 {
    
     name: 'B', stock: 1 }, 
 {
    
     name: 'A', stock: 33 }, 
 {
    
     name: 'B', stock: 2 }, 
 {
    
     name: 'C', stock: 0 }
 ];
// 第一种方式
 arr.forEach(v => obj[v.name] = obj[v.name] === undefined ? v.stock : obj[v.name] + v.stock)
 console.log(obj) 
// 第二种方法
arr.forEach(v=>{
    
    
 	if (obj.hasOwnProperty(v.name)) {
    
    
         obj[v.name] += v.stock
     } else{
    
    
        obj [v.name] = v.stock
     }
 })
console.log(obj)