Remove comma from last result in nested forEach loop

Question

I'm trying to return the following values to insert in a SQL statement:

('apple', 'fruit', '[email protected]'), ('carrot', 'vegetables', '[email protected]'), ('beans', 'vegetables', '[email protected]'), ('milk', 'dairy', '[email protected]'), ('cheese', 'dairy', '[email protected]')

Here's the data I have to work with:

const email = "[email protected]";
const body = {
        "fruit": ["apple"],
        "vegetables": ["carrot", "beans"],
        "dairy": ["milk", "cheese"]
}; 

Here's what I've tried so far:

let values = '';

Object.keys(body).forEach(key => {
  Object.keys(body[key]).forEach(item => {
    values += `('${body[key][item]}', '${key}', '${email}'),`;
  });
});

This returns the correct values, but the last result has a comma on the end which causes the an error when inserted into the SQL.

Any ideas how to rewrite this function to trim the comma from the last iteration? Maybe I should try a different loop, like for(), instead of forEach?

Thanks :)

Answer 1

I'd use map/join:

const email = "[email protected]";
const body = {
  "fruit": ["apple"],
  "vegetables": ["carrot", "beans"],
  "dairy": ["milk", "cheese"]
}; 

const values = Object.keys(body)
	.map(key => 
		body[key]
		.map(item => `('${item}', '${key}', '${email}')`)
		.join(', ')
	)
	.join(', ');

console.log(values);