util.MIMEParams.set

name: string,

value: string

): void;

Sets the value in the MIMEParams object associated with name to value. If there are any pre-existing name-value pairs whose names are name, set the first such pair's value to value.

import { MIMEType } from 'node:util';

const { params } = new MIMEType('text/plain;foo=0;bar=1');
params.set('foo', 'def');
params.set('baz', 'xyz');
console.log(params.toString());
// Prints: foo=def;bar=1;baz=xyz