Add option to set value for limiting title length (#671)

Related to #663

config.js

@@ -11,6 +11,7 @@ module.exports = {
     // 是否显示 Debug 信息，取值 boolean 'false' 'key' ，取值为 'false' false 时永远不显示，取值为 'key' 时带上 ?debug=key 显示
     debugInfo: process.env.DEBUG_INFO || true,
     sentry: process.env.SENTRY || '', // 使用 sentry 进行错误追踪，这里是 sentry 提供的 DSN 链接
+    titleLengthLimit: process.env.TITLE_LENGTH_LIMIT || 100,
     redis: {
         url: process.env.REDIS_URL || 'redis://localhost:6379/',
         options: {

docs/en/install/README.md

@@ -355,6 +355,8 @@ Use environment variables is recommended to avoid conflicts during upgrade.
 
 `LISTEN_INADDR_ANY`: open up for external access, default to `1`
 
+`TITLE_LENGTH_LIMIT`: limit the length of feed title generated in bytes, an English alphabet counts as 1 byte, the rest such as Chinese, Japanese, Korean or Arabic counts as 2 bytes by design, default to `100`
+
 `REDIS_URL`: Redis target address（invalid when `CACHE_TYPE` is set to memory）, default to `redis://localhost:6379/`
 
 `REDIS_PASSWORD`: Redis password（invalid when `CACHE_TYPE` is set to memory)

docs/install/README.md

@@ -355,9 +355,11 @@ gcloud app deploy
 
 `CACHE_TYPE`: 缓存类型, 可为 `memory` 和 `redis`, 设为空可以禁止缓存, 默认为 `memory`
 
-`CACHE_EXPIRE`: 缓存过期时间, 单位为秒, 默认 300
+`CACHE_EXPIRE`: 缓存过期时间, 单位为秒, 默认 `300`
 
-`LISTEN_INADDR_ANY`: 是否允许公网连接, 默认 1
+`LISTEN_INADDR_ANY`: 是否允许公网连接, 默认 `1`
+
+`TITLE_LENGTH_LIMIT`: 限制输出标题的字节长度, 一个英文字符的长度为 1 字节, 部分语言如中文, 日文, 韩文或阿拉伯文等, 统一算作 2 字节, 默认 `100`
 
 `REDIS_URL`: Redis 连接地址（memory 缓存类型时无效）, 默认为 `redis://localhost:6379/`
 

middleware/template.js

@@ -33,7 +33,7 @@ module.exports = async (ctx, next) => {
         ctx.state.data.item.forEach((item) => {
             for (let length = 0, i = 0; i < item.title.length; i++) {
                 length += Buffer.from(item.title[i]).length !== 1 ? 2 : 1;
-                if (length > 100) {
+                if (length > config.titleLengthLimit) {
                     item.title = `${item.title.slice(0, i)}...`;
                     break;
                 }