20. var support = ''; if ('localStorage' in window) support += 'Local Storage; '; if ('globalStorage' in window) support += 'Global Storage; '; if ('sessionStorage' in window) support += 'Session Storage; '; if ('openDatabase' in window) support += 'Database; '; document.write(support);
21. // 获取文本框 var field = document.getElementById("field"); // 在刷新后,重新取得保存的值 if ( sessionStorage.autosave ) { // 恢复自动保存的文本 field.value = sessionStorage.autosave; } // 每秒钟保存一次文字 setInterval(function(){ // 保存 sessionStorage.autosave = field.value; }, 1000);