deprecate onerror - fixes sveltejs#1745

Author: Rich-Harris

src/compile/index.ts

@@ -5,19 +5,16 @@ import renderDOM from './render-dom/index';
 import renderSSR from './render-ssr/index';
 import { CompileOptions, Warning, Ast } from '../interfaces';
 import Component from './Component';
+import deprecate from '../utils/deprecate';
 
 function normalize_options(options: CompileOptions): CompileOptions {
 	let normalized = assign({ generate: 'dom', dev: false }, options);
-	const { onwarn, onerror } = normalized;
+	const { onwarn } = normalized;
 
 	normalized.onwarn = onwarn
 		? (warning: Warning) => onwarn(warning, default_onwarn)
 		: default_onwarn;
 
-	normalized.onerror = onerror
-		? (error: Error) => onerror(error, default_onerror)
-		: default_onerror;
-
 	return normalized;
 }
 
@@ -29,10 +26,6 @@ function default_onwarn({ start, message }: Warning) {
 	}
 }
 
-function default_onerror(error: Error) {
-	throw error;
-}
-
 function validate_options(options: CompileOptions, stats: Stats) {
 	const { name, filename } = options;
 
@@ -52,7 +45,17 @@ function validate_options(options: CompileOptions, stats: Stats) {
 	}
 }
 
-export default function compile(source: string, options: CompileOptions) {
+export default function compile(source: string, options: CompileOptions = {}) {
+	const onerror = options.onerror || (err => {
+		throw err;
+	});
+
+	if (options.onerror) {
+		// TODO remove in v3
+		deprecate(`Instead of using options.onerror, wrap svelte.compile in a try-catch block`);
+		delete options.onerror;
+	}
+
 	options = normalize_options(options);
 
 	const stats = new Stats({
@@ -88,7 +91,6 @@ export default function compile(source: string, options: CompileOptions) {
 
 		return renderDOM(component, options);
 	} catch (err) {
-		options.onerror(err);
-		return;
+		onerror(err);
 	}
 }

src/compile/wrapModule.ts

@@ -276,18 +276,17 @@ function getCompatibilityStatements(dependencies: Dependency[]) {
 }
 
 function getGlobals(dependencies: Dependency[], options: CompileOptions) {
-	const { globals, onerror, onwarn } = options;
+	const { globals, onwarn } = options;
 	const globalFn = getGlobalFn(globals);
 
 	return dependencies.map(d => {
 		let name = globalFn(d.source);
 
 		if (!name) {
 			if (d.name.startsWith('__import')) {
-				const error = new Error(
+				throw new Error(
 					`Could not determine name for imported module '${d.source}' – use options.globals`
 				);
-				onerror(error);
 			} else {
 				const warning = {
 					code: `options-missing-globals`,

src/index.ts

@@ -1,24 +1,30 @@
 import compile from './compile/index';
 import { CompileOptions } from './interfaces';
+import deprecate from './utils/deprecate';
 
 export function create(source: string, options: CompileOptions = {}) {
-	options.format = 'eval';
-
-	const compiled = compile(source, options);
+	const onerror = options.onerror || (err => {
+		throw err;
+	});
 
-	if (!compiled || !compiled.js.code) {
-		return;
+	if (options.onerror) {
+		// TODO remove in v3
+		deprecate(`Instead of using options.onerror, wrap svelte.create in a try-catch block`);
+		delete options.onerror;
 	}
 
+	options.format = 'eval';
+
 	try {
-		return (new Function(`return ${compiled.js.code}`))();
-	} catch (err) {
-		if (options.onerror) {
-			options.onerror(err);
+		const compiled = compile(source, options);
+
+		if (!compiled || !compiled.js.code) {
 			return;
-		} else {
-			throw err;
 		}
+
+		return (new Function(`return ${compiled.js.code}`))();
+	} catch (err) {
+		onerror(err);
 	}
 }
 

src/interfaces.ts

@@ -60,10 +60,10 @@ export interface CompileOptions {
 
 	preserveComments?: boolean | false;
 
-	onerror?: (error: Error) => void;
 	onwarn?: (warning: Warning) => void;
 
 	// to remove in v3
+	onerror?: (error: Error) => void;
 	skipIntroByDefault?: boolean;
 	nestedTransitions?: boolean;
 }

src/utils/deprecate.ts

@@ -0,0 +1,8 @@
+const seen = new Set();
+
+export default function deprecate(message: string, code = message) {
+	if (seen.has(code)) return;
+	seen.add(code);
+
+	console.warn(`[svelte] DEPRECATION: ${message}`);
+}

test/parser/index.js

@@ -48,6 +48,7 @@ describe('parse', () => {
 		});
 	});
 
+	// TODO remove in v3
 	it('handles errors with options.onerror', () => {
 		let errored = false;
 
@@ -61,6 +62,7 @@ describe('parse', () => {
 		assert.ok(errored);
 	});
 
+	// TODO remove in v3
 	it('throws without options.onerror', () => {
 		assert.throws(() => {
 			svelte.compile(`<h1>unclosed`);