feat(full_url_for): bring up a new helper (#84)

* feat(full_url_for): bring up a new helper

README.md

@@ -61,6 +61,20 @@ Escapes diacritic characters in a string.
 
 Escapes HTML entities in a string.
 
+### full_url_for(path)
+
+Returns a url with the config.url prefixed. Output is [encoded](#encodeurlstr) automatically.
+
+``` yml
+_config.yml
+url: https://example.com/blog # example
+```
+
+``` js
+full_url_for('/a/path')
+// https://example.com/blog/a/path
+```
+
 ### hash(str)
 
 Generates SHA1 hash.

lib/full_url_for.js

@@ -0,0 +1,18 @@
+'use strict';
+
+const { parse } = require('url');
+const encodeURL = require('./encode_url');
+
+function fullUrlForHelper(path = '/') {
+  if (path.startsWith('//')) return path;
+  const { config } = this;
+  const data = parse(path);
+
+  // Exit if this is an external path
+  if (data.protocol) return path;
+
+  path = encodeURL(config.url + `/${path}`.replace(/\/{2,}/g, '/'));
+  return path;
+}
+
+module.exports = fullUrlForHelper;

lib/index.js

@@ -10,6 +10,7 @@ exports.encodeURL = require('./encode_url');
 exports.escapeDiacritic = require('./escape_diacritic');
 exports.escapeHTML = require('./escape_html');
 exports.escapeRegExp = require('./escape_regexp');
+exports.full_url_for = require('./full_url_for');
 exports.hash = hash.hash;
 exports.HashStream = hash.HashStream;
 exports.highlight = require('./highlight');

test/full_url_for.spec.js

@@ -0,0 +1,40 @@
+'use strict';
+
+describe('full_url_for', () => {
+  const ctx = {
+    config: {}
+  };
+
+  const fullUrlFor = require('../lib/full_url_for').bind(ctx);
+
+  it('internal url - root directory', () => {
+    ctx.config.url = 'https://example.com';
+    fullUrlFor('index.html').should.eql(ctx.config.url + '/index.html');
+    fullUrlFor('/').should.eql(ctx.config.url + '/');
+  });
+
+  it('internal url - subdirectory', () => {
+    ctx.config.url = 'https://example.com/blog';
+    fullUrlFor('index.html').should.eql(ctx.config.url + '/index.html');
+    fullUrlFor('/').should.eql(ctx.config.url + '/');
+  });
+
+  it('internal url - no duplicate slash', () => {
+    ctx.config.url = 'https://example.com';
+    fullUrlFor('/index.html').should.eql('https://example.com/index.html');
+  });
+
+  it('external url', () => {
+    [
+      'https://hexo.io/',
+      '//google.com/'
+    ].forEach(url => {
+      fullUrlFor(url).should.eql(url);
+    });
+  });
+
+  it('only hash', () => {
+    ctx.config.url = 'https://example.com/blog';
+    fullUrlFor('#test').should.eql(ctx.config.url + '/#test');
+  });
+});