JSLint, The JavaScript Code Quality and Coverage Tool

Douglas Crockford douglas@crockford.com

Status

Branch	master (v2021.12.20)	beta (Web Demo)	alpha (Development)
CI
Coverage
Demo
Artifacts

Table of Contents

1. Web Demo

2. Web Demo Archived

3. API Doc

4. Quickstart Install

   • To install, just download https://www.jslint.com/jslint.mjs and save to file:
   • To run jslint.mjs in shell:
   • To import jslint.mjs in ES Module environment:
   • To import jslint.mjs in CommonJS environment:
   • To JSLint entire directory in shell:

5. Quickstart JSLint Report

   • To create a JSLint report in shell:
   • To create a JSLint report in javascript:

6. Quickstart V8 Coverage Report

   • To create V8 coverage report from Node.js / Npm program in shell:
   • To create V8 coverage report from Node.js / Npm program in javascript:

7. Quickstart JSLint in Vim

   • To run JSLint in Vim:

8. Description

9. Package Listing

10. Changelog

11. License

Web Demo

• https://www.jslint.com

Web Demo Archived

• Web Demo 2020
• Web Demo 2014 (ES5 only)
• Web Demo 2013 (ES5, CSS, HTML)

API Doc

• https://www.jslint.com/apidoc.html

Quickstart Install

To install, just download https://www.jslint.com/jslint.mjs and save to file:

#!/bin/sh

curl -L https://www.jslint.com/jslint.mjs > jslint.mjs

• shell output

To run jslint.mjs in shell:

#!/bin/sh

printf "console.log('hello world');\n" > hello.js

node jslint.mjs hello.js

• shell output

To import jslint.mjs in ES Module environment:

#!/bin/sh

node --input-type=module --eval '

/*jslint devel*/

// Import JSLint in ES Module environment.

import jslint from "./jslint.mjs";

let globals = ["caches", "indexedDb"];
let options = {browser: true};
let result;
let source = "console.log(\u0027hello world\u0027);\n";

// JSLint <source> and print <formatted_message>.

result = jslint.jslint(source, options, globals);
result.warnings.forEach(function ({
    formatted_message
}) {
    console.error(formatted_message);
});

'

• shell output

To import jslint.mjs in CommonJS environment:

#!/bin/sh

node --eval '

/*jslint devel*/
(async function () {
    let globals = ["caches", "indexedDb"];
    let jslint;
    let options = {browser: true};
    let result;
    let source = "console.log(\u0027hello world\u0027);\n";

// Import JSLint in CommonJS environment.

    jslint = await import("./jslint.mjs");
    jslint = jslint.default;

// JSLint <source> and print <formatted_message>.

    result = jslint.jslint(source, options, globals);
    result.warnings.forEach(function ({
        formatted_message
    }) {
        console.error(formatted_message);
    });
}());

'

• shell output

To JSLint entire directory in shell:

#!/bin/sh

# JSLint directory '.'

node jslint.mjs .

• shell output

Quickstart JSLint Report

To create a JSLint report in shell:

#!/bin/sh

printf "function foo() {console.log('hello world');}\n" > hello.js

# Create JSLint report from file 'hello.js' in shell.

node jslint.mjs \
    jslint_report=.artifact/jslint_report_hello.html \
    hello.js

• shell output

• screenshot file .artifact/jslint_report_hello.html

To create a JSLint report in javascript:

#!/bin/sh

node --input-type=module --eval '

/*jslint devel*/
import jslint from "./jslint.mjs";
import fs from "fs";
(async function () {
    let report;
    let result;
    let source = "function foo() {console.log(\u0027hello world\u0027);}\n";

// Create JSLint report from <source> in javascript.

    result = jslint.jslint(source);
    report = jslint.jslint_report(result);

    await fs.promises.mkdir(".artifact/", {recursive: true});
    await fs.promises.writeFile(".artifact/jslint_report_hello.html", report);
    console.error("wrote file .artifact/jslint_report_hello.html");
}());

'

• shell output

• screenshot file .artifact/jslint_report_hello.html

Quickstart V8 Coverage Report

To create V8 coverage report from Node.js / Npm program in shell:

#!/bin/sh

git clone https://github.com/mapbox/node-sqlite3 node-sqlite3-sh \
    --branch=v5.0.2 \
    --depth=1 \
    --single-branch

cd node-sqlite3-sh
npm install

# Create V8 coverage report from program `npm run test` in shell.

node ../jslint.mjs \
    v8_coverage_report=../.artifact/coverage_sqlite3_sh/ \
    --exclude-node-modules=true \
    --exclude=test/foo.js,test/bar.js \
    --exclude=test/baz.js \
    npm run test

• shell output

• screenshot file .artifact/coverage_sqlite3_sh/index.html

• screenshot file .artifact/coverage_sqlite3_sh/lib/sqlite3.js.html

To create V8 coverage report from Node.js / Npm program in javascript:

#!/bin/sh

git clone https://github.com/mapbox/node-sqlite3 node-sqlite3-js \
    --branch=v5.0.2 \
    --depth=1 \
    --single-branch

cd node-sqlite3-js
npm install

node --input-type=module --eval '

/*jslint node*/
import jslint from "../jslint.mjs";
(async function () {

// Create V8 coverage report from program `npm run test` in javascript.

    await jslint.v8CoverageReportCreate({
        coverageDir: "../.artifact/coverage_sqlite3_js/",
        processArgv: [
            "--include=lib/sqlite3-binding.js,lib/sqlite3.js",
            "--include=lib/trace.js",
            "npm", "run", "test"
        ]
    });
}());

'

• shell output

• screenshot file .artifact/coverage_sqlite3_js/index.html

• screenshot file .artifact/coverage_sqlite3_js/lib/sqlite3.js.html

Quickstart JSLint in Vim

To run JSLint in Vim:

1. Download and save jslint.mjs, jslint_wrapper_vim.vim to directory ~/.vim/
2. Add vim-command :source ~/.vim/jslint_wrapper_vim.vim to file ~/.vimrc
3. Vim can now jslint files (via nodejs):
   • with vim-command :SaveAndJslint
   • with vim-key-combo <Ctrl-S> <Ctrl-J>

• screenshot

Description

• jslint.mjs contains the jslint function. It parses and analyzes a source file, returning an object with information about the file. It can also take an object that sets options.

• index.html runs the jslint.mjs function in a web page.

• help.html describes JSLint's usage. Please read it.

JSLint can be run anywhere that JavaScript (or Java) can run.

The place to express yourself in programming is in the quality of your ideas and the efficiency of their execution. The role of style in programming is the same as in literature: It makes for better reading. A great writer doesn't express herself by putting the spaces before her commas instead of after, or by putting extra spaces inside her parentheses. A great writer will slavishly conform to some rules of style, and that in no way constrains her power to express herself creatively. See for example William Strunk's The Elements of Style [https://www.crockford.com/style.html].

This applies to programming as well. Conforming to a consistent style improves readability, and frees you to express yourself in ways that matter. JSLint here plays the part of a stern but benevolent editor, helping you to get the style right so that you can focus your creative energy where it is most needed.

Package Listing

Changelog

• Full CHANGELOG.md

License

• JSLint is under Unlicense License.
• CodeMirror editor is under MIT License.
• Function v8CoverageListMerge is derived from MIT Licensed v8-coverage.