[BUG] Deprecated function used in JavaScript and TypeScript generators

[possan]

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

The current JavaScript and TypeScript generators use substr to get the date part (YYYY-MM-DD) from a full ISO-8601 date string, substr is deprecated and there is a substring function that is supported and that should be used instead.

Using deprecated functions might blocked by your build system.

Reference: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/substr

openapi-generator version

Tested 6.6.0 and Master - Not a regression

Steps to reproduce

Generate any spec file containing a date field, the code generated is:

httpParams = httpParams.append(key, (value as Date).toISOString().substr(0, 10));

Related issues/PRs

Found no issue or PR mentioning this

Suggest a fix

Draft PR: #15937

[possan]

PR was merged #15937