Dynamically add new array to existing object array React JS

Question

I am getting the value of id and quantity during the click button. I want add a new array inside the object array. Below is the code

adddata =(d,v) => {

    const product = [];

    for (let i = 0; i < 1; i++) {

    product.push({
                   product_id:d,    
                   cart_quantity:v
            });
        }
console.log(product);


<button value={this.state.quantity} className="btn" onClick={adddata} data-id={item.product_id}>Add to cart</button>

The only issue with this implementation is that. it replacing the new value with an existing one. I want to merge it dynamically every time click on the button.

Please help

Answer 1

You defined the variable product inside the function, So each time when you execute the function, It will be reinitialized.

Use Global Variable / State

// global
const product = [];

addData =(d,v) => {

    // I removed the loop because it's useless here.

    product.push({
       product_id:d,    
       cart_quantity:v
    });
}