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ツイートボタン不具合 - niconicoの不具合報告掲示板

prototype.js 1.6 と platform.twitter.com/widgets.js の組み合わせはエラーが出て
ツイートボタンが表示されない。

All of the web pages shared in this thread that are experiencing issues are using prototype.js 1.6. That library overrides Array.prototype.reduce with a non-standard implementation which results in widgets.js setting the source of images to undefined.

Timeline widget stopped to show pictures - Twitter for Websites - Twitter Developers