OpenInNewWindow(data, type) - F5-REFRESHABLE! - auto-UTF8 if type==="text"! - also ContentsInNewWindow(contents = '' or [], Title, type, delimToJoinArray = "\n\n")

contentsInNewWindow.js

// contentsInNewWindow.js - F5-REFRESHABLE! - with TITLE! - (contents = '' or [], title, type = 'octet-stream', array-joining-delim = '\n\n')

// const contentsInNewWindow=(c=[],T,t="octet-stream",d="\n\n")=>{const w=open(URL.createObjectURL(new Blob([[c].flat(1/0).join(d)],{type:"text"===t?t+"/plain;charset=utf-8":t})),"_blank");return w&&!w.closed&&(w.onload=()=>w.document.title=T),w};
const contentsInNewWindow = (contents = [], title, type = ["text", "octet-stream"][1], delim = "\n\n") => {
	const win = open(
		URL.createObjectURL(
			new Blob([
				[contents].flat(1/0).join(delim)
			], {
				// auto-UTF8 if type === 'text', to easily ensure visible emojis etc.
				type: type !== "text" ? type : (type + "/plain;charset=utf-8")
			})
		)
		, "_blank"	// new tab for [blob:<location.origin>/abc-12-34-def]
	);
	if(win && !win.closed)win.onload = () => win.document.title = title;
	return win;
};
// var s = "🤦‍♂🌞have a great weekend   "; console.log(s); console.log(s = new Blob([s], {type: "text/plain; charset=utf-8"}), s = URL.createObjectURL(s)); window.open(s); !!s;
// new tab:	"🤦‍♂🌞have a great weekend   "
// Blob {size: 37, type: 'text/plain; charset=utf-8'} 'blob:<location.origin>/abc-12-34-def'
// 🤦‍♂🌞have a great weekend   
// returns:	true



var string = "🤦‍♂🌞have a great weekend   ";
var array = ["🤦‍♂", "🌞", "have a great weekend   "];
var joiner = "[-_-]";

console.log(contentsInNewWindow(string, "<title: default type 'octet-stream' AKA 'application/octet-binary'>"));
// new tab:	"🤦‍♂🌞have a great weekend   "
// returns:	Window {window: Window, self: Window, document: document, name: '', location: Location, ...}

console.log(contentsInNewWindow(string, "<title: text/plain which defaults to ;ascii>", "text/plain"));
// new tab:	"🤦‍♂🌞have a great weekend   "
// returns:	Window {window: Window, self: Window, document: document, name: '', location: Location, ...}

console.log(contentsInNewWindow(string, "<title: auto-UTF8 - type 'text' expands to 'text/plain;utf-8'>", "text"));
// new tab:	"🤦‍♂🌞have a great weekend   "
// returns:	Window {window: Window, self: Window, document: document, name: '', location: Location, ...}

console.log(contentsInNewWindow(array, "<title: auto-UTF8 & array-joining delim>", "text", joiner));
// new tab:	"🤦‍♂[-_-]🌞[-_-]have a great weekend   "
// returns:	Window {window: Window, self: Window, document: document, name: '', location: Location, ...}

contentsInNewWindow_FINAL.js

// contentsInNewWindow.js -- both possibilities compared(ALL survive F5 refresh)

C1=(...strings)=>{let a=document.createElement("a");a.href=URL.createObjectURL(new Blob([strings.join("\n")]),{type:"text/plain;charset=utf-8"}),a.target="_blank",a.click()};
// ^ 170 chars

C1b=(...strings)=>Object.assign(document.createElement("a"),{href:URL.createObjectURL(new Blob([strings.join("\n")],{type:"text/plain;charset=utf-8"})),target:"_blank"}).click();
// ^ 173 chars so forget this "TRICK"

C2=(...strings)=>open(URL.createObjectURL(new Blob([strings.join("\n")],{type:"text/plain;charset=utf-8"})),"_blank");
// ^ 114 chars

C3=(title,...strings)=>{let w=open(URL.createObjectURL(new Blob([strings.join("\n")],{type:"text/plain;charset=utf-8"})),"_blank");w&&!w.closed&&(w.onload=_=>{title&&(w.document.title=title)})};
// ^ 190 chars

C3b=(title,...strings)=>[open(URL.createObjectURL(new Blob([strings.join("\n")],{type:"text/plain;charset=utf-8"})),"_blank")].map(w=>w&&!w.closed&&(w.onload=_=>{title&&(w.document.title=title)}));

// ^ 192 chars so forget this "TRICK"

openInNewWindow.js

// openInNewWindow.js - F5-REFRESHABLE! - (data, type = 'octet-stream')

// const openInNewWindow=(d,t="octet-stream")=>Object.assign(document.createElement("a"),{href:URL.createObjectURL(new Blob([d].slice(d===void 0),{type:"text"===t?t+"/plain;charset=utf-8":t})),target:"_blank"}).click();
const openInNewWindow = (data, type = ["text", "octet-stream"][1]) => Object.assign(
	document.createElement("a"), {
		href: URL.createObjectURL(
			new Blob([data].slice(data === undefined), {
				// auto-UTF8 if type === 'text', to easily ensure visible emojis etc.
				type: type !== "text" ? type : (type + "/plain;charset=utf-8")
			})
		)
		// , filename: <omitted> = DISPLAY data in browser instead of saving file - e.g. [blob:<location.origin>/abc-12-34-def]
		, target: "_blank"	// new tab for [blob:<location.origin>/abc-12-34-def]
	}
).click();
// var s = "🤦‍♂🌞have a great weekend   "; console.log(s); console.log(s = new Blob([s], {type: "text/plain; charset=utf-8"}), s = URL.createObjectURL(s)); window.open(s); !!s;
// new tab:	"🤦‍♂🌞have a great weekend   "
// Blob {size: 37, type: 'text/plain; charset=utf-8'} 'blob:<location.origin>/abc-12-34-def'
// 🤦‍♂🌞have a great weekend   
// returns:	true



var string = "🤦‍♂🌞have a great weekend   ";
var array = ["🤦‍♂", "🌞", "have a great weekend   "];

console.log(openInNewWindow(string));	// default type 'octet-stream' AKA 'application/octet-binary'
// new tab:	"🤦‍♂🌞have a great weekend   "
// returns:	undefined

console.log(openInNewWindow(string, "text/plain"));	// text/plain which defaults to ;ascii
// new tab:	"🤦‍♂🌞have a great weekend   "
// returns:	undefined

console.log(openInNewWindow(string, "text"));	// auto-UTF8 - type 'text' expands to 'text/plain;utf-8'
// new tab:	"🤦‍♂🌞have a great weekend   "
// returns:	undefined

console.log(openInNewWindow(array, "text"));	// auto-UTF8 - type 'text' expands to 'text/plain;utf-8'
// new tab:	"🤦‍♂,🌞,have a great weekend   "
// returns:	undefined



/////// examples with simple textString (output = various values for MIME type; some open SaveAs dialog)

var textString = "\nthe\n\n\tcontents";

// display text inside new tab
openInNewWindow(textString);

// display text AS PNG (will not be usable, of course) inside new tab
openInNewWindow(textString, "image/png");

// display text AS ZIP (will prompt to download, because .ZIP!) inside new tab
openInNewWindow(textString, "application/zip");

// display text AS Windows' custom MIME type for ZIP (will prompt to download, because .ZIP!) inside new tab
openInNewWindow(textString, "application/x-zip-compressed");