Enhanced loader for Eruda

[MasterInQuestion]

    Enhanced loader for Eruda, in bookmarklet form.
    Attempt to workaround Eruda not loading due to site's CSP (Content Security Policy) configuration.

    When remote loading prevented by CSP, fallback attempts to retrieve Eruda's content from a local file.
    2 approaches initializing the script are tried:
    |1| Text in "<script>" element, inject and load. [1]
    |2| (if didn't work) Directly execute the script's text.
[1] Probably not much performance difference. Mostly for demo.

[[
javascript: (function () { window.define = undefined; var x0, x1, x = { defaults: { displaySize: 50 } }, x2 = ".eruda-container * { user-select: text !important; }", body = document.getElementsByTagName( "body" )[0]; body.appendChild( x0 = document.createElement( "script" ) ); x0.src = "https://cdn.jsdelivr.net/npm/eruda"; x0.onload = function () { eruda.init( x ); eruda.util.evalCss( x2 ); }; x0.onerror = function () { this.parentNode.removeChild( this ); body.appendChild( x0 = document.createElement( "input" ) ); x0.type = "file"; x0.onchange = function () { this.parentNode.removeChild( this ); x1 = new FileReader(); x1.onload = function () { x1 = x1.result + "\neruda.init(" + JSON.stringify( x ) + ");" + ' eruda.util.evalCss( "' + x2.replace( /(?=["\\])/g, '\\' ) + '" );'; try { body.appendChild( x0 = document.createElement( "script" ) ); x0.text = x1; } catch ( e ) {}; if ( "eruda" in window === false ) { x0.parentNode.removeChild( x0 ); Function( x1 )(); }; }; x1.readAsText( this.files[0] ); }; x0.style = "z-index: 2147483647; position: fixed; bottom: 0"; x0.click(); }; })();
]]

    Unrolled and commented:
[[

	(function () {
// >>>> (0)
	window.define = undefined;
	var x0, x1,
	x = { defaults: { displaySize: 50 } },
	x2 = ".eruda-container * { user-select: text !important; }",
// ^ https://github.com/liriliri/eruda/issues/461
	body = document.getElementsByTagName( "body" )[0];

	body.appendChild( x0 = document.createElement( "script" ) );
	x0.src = "https://cdn.jsdelivr.net/npm/eruda";
	x0.onload = function () { eruda.init( x ); eruda.util.evalCss( x2 ); };
	x0.onerror = function () {
// >>>> (1)
	this.parentNode.removeChild( this );
// Choose downloaded [ https://cdn.jsdelivr.net/npm/eruda ] for the file input.
	body.appendChild( x0 = document.createElement( "input" ) );
	x0.type = "file";
	x0.onchange = function () {
// >>>> (2)
	this.parentNode.removeChild( this );
	x1 = new FileReader();

	x1.onload = function () {
// >>>> (3)
	x1 = x1.result + "\neruda.init(" + JSON.stringify( x ) + ");" +
	' eruda.util.evalCss( "' + x2.replace( /(?=["\\])/g, '\\' ) + '" );';
	try {
	body.appendChild( x0 = document.createElement( "script" ) );
	x0.text = x1;
	} catch ( e ) {};

// "error" event does not trigger, so:
	if ( "eruda" in window === false ) {
// Guessed condition.
	x0.parentNode.removeChild( x0 );
	Function( x1 )(); // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/eval#never_use_direct_eval!
	};
// <<<< (3)
	};

	x1.readAsText( this.files[0] );
// <<<< (2)
	};

	x0.style = "z-index: 2147483647; position: fixed; bottom: 0";
	x0.click(); // May not work for certain browsers; attempted anyway.
// <<<< (1)
	};
// <<<< (0)
	})();

]]

    All `${Node}.parentNode.removeChild( ${Node} );` parts are not really necessary: merely included for saner DOM tree.
    See also:
    https://github.com/liriliri/eruda/discussions/326
    https://github.com/liriliri/eruda/issues/13

    Note Eruda expects "window.define" be undefined.
    See: https://github.com/liriliri/eruda/issues/143

    CSP failure may be critical so wrap "try { ... } catch ( e ) {};".
    [ https://caniuse.com/?search=try...catch ]

    Added extra handling of 2 minor improvements:
    |1| More reasonable default "displaySize".
    |2| Resolving potential misuse of "user-select: none".

[MasterInQuestion]

    Derived cut-down version that directly attempts execute the script's text:
    javascript: (function () { window.define = undefined; var x0, x1, body = document.getElementsByTagName( "body" )[0]; body.appendChild( x0 = document.createElement( "script" ) ); x0.src = "https://cdn.jsdelivr.net/npm/eruda"; x0.onload = function () { eruda.init(); }; x0.onerror = function () { this.parentNode.removeChild( this ); body.appendChild( x0 = document.createElement( "input" ) ); x0.type = "file"; x0.onchange = function () { this.parentNode.removeChild( this ); x1 = new FileReader(); x1.onload = function () { Function( x1.result + "\neruda.init();" )(); }; x1.readAsText( this.files[0] ); }; x0.style = "z-index: 2147483647; position: fixed; bottom: 0"; x0.click(); }; })();

[[

	(function () {
// >>>> (0)
	window.define = undefined;
	var x0, x1,
	body = document.getElementsByTagName( "body" )[0];

	body.appendChild( x0 = document.createElement( "script" ) );
	x0.src = "https://cdn.jsdelivr.net/npm/eruda";
	x0.onload = function () { eruda.init(); };
	x0.onerror = function () {
// >>>> (1)
	this.parentNode.removeChild( this );
// Choose downloaded [ https://cdn.jsdelivr.net/npm/eruda ] for the file input.
	body.appendChild( x0 = document.createElement( "input" ) );
	x0.type = "file";
	x0.onchange = function () {
// >>>> (2)
	this.parentNode.removeChild( this );
	x1 = new FileReader();

	x1.onload = function () {
	Function( x1.result + "\neruda.init();" )();
	// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/eval#never_use_direct_eval!
	};

	x1.readAsText( this.files[0] );
// <<<< (2)
	};

	x0.style = "z-index: 2147483647; position: fixed; bottom: 0";
	x0.click(); // May not work for certain browsers; attempted anyway.
// <<<< (1)
	};
// <<<< (0)
	})();

]]

    Note this may fail for no "unsafe-eval".
    [ https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy/script-src#unsafe_eval_expressions ]