Retrieving the Default Export in JavaScriptCore

Question

Retrieving the Default Export in JavaScriptCore

Objective: My goal is to implement JSLint within JavaScriptCore.

Previous Iteration

Earlier versions of JSLint featured a global function named JSLINT, defined as follows:

var JSLINT = (function () {
    ...
}

Accessing and executing this function in JavaScriptCore was straightforward:

// Assuming 'ctx' is a JSGlobalContextRef
// Assuming JSEvaluateScript() has already been called

JSStringRef jsFunctionName = JSStringCreateWithUTF8CString("JSLINT");
JSValueRef jsLintFunctionValue = JSObjectGetProperty(ctx, JSContextGetGlobalObject(ctx), jsFunctionName, NULL);
JSStringRelease(jsFunctionName);
    
JSObjectRef jsLintFunction = JSValueToObject(ctx, jsLintFunctionValue, &exception);

Having obtained this reference, I could then utilize JSObjectCallAsFunction() to execute the function with success.

Current Version

Presently, JSLint has transitioned to the following structure:

export default Object.freeze(function jslint(
    source = "",
    option_object = empty(),
    global_array = []
) { 
    ... 
});

The resources for JavaScriptCore are lacking in clarity. Despite multiple attempts, I am evidently overlooking some essential aspect. How can I retrieve and run the jslint function now?

javascript c jslint javascriptcore

Answer 1

Answer №1

Quick version

If you didn't find what you were looking for in @kaizhu's answer, there is another approach to achieve a state similar to what you had previously by...

Commenting out two lines of export code starting from this line.
Referring to lower-case jslint

These are the two lines that need to be commented out with the current version of JSLint.

// export default Object.freeze(jslint_export);
// jslint_import_meta_url = import.meta.url;

By including this edited file in your project now, the function jslint will be in your global scope.

console.log(JSON.stringify(jslint("var a = 5").warnings, null, "  "))

Results:

[
  {
    "a": ";",
    "b": "(end)",
    "code": "expected_a_b",
    "column": 9,
    "line": 1,
    "line_source": "var a = 5",
    "name": "JSLintError",
    "message": "Expected ';' and instead saw '(end)'.",
    "formatted_message": " 1. \u001b[31mExpected ';' and instead saw '(end)'.\u001b[39m \u001b[90m// line 1, column 9\u001b[39m\n    var a = 5"
  }
]

The only change I believe you need to make to your code is to use lower-case jslint:

JSStringRef jsFunctionName = JSStringCreateWithUTF8CString("jslint");

Improvements?

It may actually be more correct to utilize jslint_export, which is a frozen copy of jslint.

JSStringRef jsFunctionName = JSStringCreateWithUTF8CString("jslint_export");

If you prefer, you can replace the jslint_export variable with JSLINT without making any changes to your JavaScriptCore code.

// let jslint_export;              // The jslint object to be exported.
let JSLINT;                        // The jslint object to be exported.

// lots of stuff skipped

// jslint_export = Object.freeze(Object.assign(jslint, {
JSLINT = Object.freeze(Object.assign(jslint, {
    cli: Object.freeze(jslint_cli),
    edition: jslint_edition,
    jslint: Object.freeze(jslint.bind(undefined))
}));

I would need to verify if this behaves the same as the old code, but note that in this structure, the actual linting function would be on JSLINT.jslint.

I'm not sure why there is so much pollution in the global scope in the current JSLint version. It is perplexing why all this does not exist within an IIFE; I believe it used to? Regardless, this should resolve your problem.

Answer 2

Quick version

If you didn't find what you were looking for in @kaizhu's answer, there is another approach to achieve a state similar to what you had previously by...

Commenting out two lines of export code starting from this line.
Referring to lower-case jslint

These are the two lines that need to be commented out with the current version of JSLint.

// export default Object.freeze(jslint_export);
// jslint_import_meta_url = import.meta.url;

By including this edited file in your project now, the function jslint will be in your global scope.

console.log(JSON.stringify(jslint("var a = 5").warnings, null, "  "))

Results:

[
  {
    "a": ";",
    "b": "(end)",
    "code": "expected_a_b",
    "column": 9,
    "line": 1,
    "line_source": "var a = 5",
    "name": "JSLintError",
    "message": "Expected ';' and instead saw '(end)'.",
    "formatted_message": " 1. \u001b[31mExpected ';' and instead saw '(end)'.\u001b[39m \u001b[90m// line 1, column 9\u001b[39m\n    var a = 5"
  }
]

The only change I believe you need to make to your code is to use lower-case jslint:

JSStringRef jsFunctionName = JSStringCreateWithUTF8CString("jslint");

Improvements?

It may actually be more correct to utilize jslint_export, which is a frozen copy of jslint.

JSStringRef jsFunctionName = JSStringCreateWithUTF8CString("jslint_export");

If you prefer, you can replace the jslint_export variable with JSLINT without making any changes to your JavaScriptCore code.

// let jslint_export;              // The jslint object to be exported.
let JSLINT;                        // The jslint object to be exported.

// lots of stuff skipped

// jslint_export = Object.freeze(Object.assign(jslint, {
JSLINT = Object.freeze(Object.assign(jslint, {
    cli: Object.freeze(jslint_cli),
    edition: jslint_edition,
    jslint: Object.freeze(jslint.bind(undefined))
}));

I would need to verify if this behaves the same as the old code, but note that in this structure, the actual linting function would be on JSLINT.jslint.

I'm not sure why there is so much pollution in the global scope in the current JSLint version. It is perplexing why all this does not exist within an IIFE; I believe it used to? Regardless, this should resolve your problem.

Answer 3

Answer №2

Learn how to incorporate jslint as an ES module by following the steps provided here.

/*jslint devel*/
import jslint from "./jslint.mjs";
let code = "console.log('hello world');\n";
let result = jslint(code);
result.warnings.forEach(function ({
    formatted_message
}) {
    console.error(formatted_message);
});

// stderr
// 1 Undeclared 'console'. // line 1, column 1
// console.log('hello world');
// 2 Use double quotes, not single quotes. // line 1, column 13
// console.log('hello world');

Answer 4

Learn how to incorporate jslint as an ES module by following the steps provided here.

/*jslint devel*/
import jslint from "./jslint.mjs";
let code = "console.log('hello world');\n";
let result = jslint(code);
result.warnings.forEach(function ({
    formatted_message
}) {
    console.error(formatted_message);
});

// stderr
// 1 Undeclared 'console'. // line 1, column 1
// console.log('hello world');
// 2 Use double quotes, not single quotes. // line 1, column 13
// console.log('hello world');

Retrieving the Default Export in JavaScriptCore

Previous Iteration

Current Version

Answer №1

Quick version

Improvements?

Answer №2

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