Are there any particular characters or sequences that should never be put in an image description?

Question

Answer(s) to How to upload an image to a post? (found in metaFAQ) explain several reasons why we should

replace the default "enter image description here" with something meaningful.

Are there any particular characters or sequences that should never be put in an image description? Things that might break the page or result in undesirable or unexpected behavior?

Answer 1

result in undesirable or unexpected behavior?

Consider the idea is screen readers should be able to read it, and it should describe the image. You're probably better off not using many of these

• Emoji 🤔

• 𝖀𝖓𝖎𝖈𝖔𝖉𝖊 𝖋𝖔𝖗 𝖘𝖎𝖒𝖚𝖑𝖆𝖙𝖎𝖓𝖌 𝖋𝖆𝖓𝖈𝖞 𝖋𝖔𝖓𝖙𝖘

• ssǝuıןןıs ɹǝɥʇo ɹO

• Of course Zalgo text, a thing so horrible I'm hiding it under a spoiler tag so it doesn't break weaker minds, or at least hide the rest of the abominations I've trotted out

  L̷̹̈͗́̎̒̉̽ë̷̢̤͕̙̬͕͎̘̳̹̳́̈́͊̌̂́̕̚̕ͅţ̷̧̢̛͇͉͖͎̥͔̫̞̠͉̗͋̃̑̍s̵̳̹̪͓͈̹̟̏͗͛̓͘ ̵̟̮͍̼̜̦̝̩̎̂̄ņ̶̝̖̣̮͍̱̫͍͑̉ǒ̵̞͖̏̚ṭ̶̨͕̄̍͊͌̈͐̋̈́̕ ̸̖̯͉̠͎̜̙͉͙̤͕̮̭͇̣̈́̔̽̽f̷̨͚̙̯̱̮͓̙̩͍͚̺͑̈́̿̉͆͜ợ̸̢̢̢̛͙̗͙͍̹̝̖̳̬̗̒̔́̌̎̈́́͐̆́͘̚͜r̵̨̘̳̺̖̝̥̮͇̙̯̜̊̅̋͐̚͜͝ͅg̵̹̦̰̗̫͌͑̏̊̾̎̓̆͆̑̏̈̚͠͠͝ȩ̷̛̖̹̖̬̳̹̺̮͈̜̩̯̹̈͂̃͌̍̊̊̽́͂̾̿̈́̚͝͠ͅt̷̛͉̺̺̜̙͇͋͆͂̌̈̑̌̂̄͂͝ ̴̭̏̋̉̂̂̀͊̈́̎̀̿͂͐͒̾̚͝t̸̨̨͖̹̰͇̭̖̜͕͖̘̘͍̭͇͔̍̏̀̂̚h̸̨̞̫̼̯͈̙̪͇̟͍̼̩̘͋͗́̉̋̅̄̒͑͗̇̋͘͠ͅͅę̷̡̪̼͔͔̪̥̜͕̫̙̝̮̼̺̀̓͊̄̋͝ ̶̡̡̭͇͉͔̝͍̻͇̩͈̬̼͛͊͛̒͊̋͂̌̈́̅͋̉̄͐͐̇͜͝ͅh̸̡̡̛̛̙̖̳̜̹̼̙̲̽͊ō̶̠̐̊́̏͗̅̿́r̶̨̳̩͕͗r̷̰̎͗̐̏̑̑̈́̂̔͘ơ̶̡̨̛̬͍̟̻̖͕͚̦̭͖̜̲̍̏̂̊̒̊́́̆̊̅̄́̏̚ṙ̶̢̩̥̝̟̪͓͈̱̥͂ͅş̸̰̟̟͇͇͗̓̋̍͋ ̷̣̗̯̝̘̘̼̐̅̉͛̂͑̕͜o̴̡̨̗̺̺̣͇͔̼̰̮̫̐̈́̓̋̽̎́f̸̨͎̬̲̹̝͓͔̮̪͎̭̿́̐̆̍͆̕ ̴̛̺͚̗̭̼̳̦̘͍͈̘̗̫̠͔̞̀͆͋̓̉͌͒͘̚͝͠ş̸̭̻̰͈͇̮̳͈͓͕̙̅̉̓̋̓̂̀̆͘͘͝ẗ̸̛͎̣̼̻͖͙͓̥͔̤͕̖͖̿̀͆͐̋̍͌͜a̵͇̍̀c̵̰͎̪̼͚͇̲͍̞͖͛̈́́̌̀͆k̷̡̢̛͔̤̯͇̫͎̤̦̞̙̦̦̙̰ͅȅ̸̝̝̪͙͓̗͈̼̟̟͖̺̎̀̈d̴͙͐̀̒̉̅͗̔͂̾͑͐̀̋̆̕̕ ̴͕̠̟͉̩̥̦̭͔̓́̄̿͗͋̎͌̄͋͗̾̀d̷̛̲̘͔̰̖̼͙̺̳͌̌i̸̡͍͉̯͗̔a̴̭̯̲̬̿̿̂̊͒̌̈̑͠c̶̡̢̥̳͉̘̻̋r̵̘͕̻̮̤̱͑̊̏̎̒͊̌͒̀̉͝i̶̛̯͙̹̊͛̒̂͆͛̽̇̋͂̈́̿͋́̒̒t̶̢̖͇͕̗͇̼̤̩͈͓̗̣͋̋̐́̈́̎̽̎́̕̚͜͝į̶̨̧̺͔̼̻̠͉̤͋͌́͒͌̓̐̏̋͊̚͝͝ć̶̡̪͖̥̪̺̄̄̿̆́̃́̾́̕̕s̸̠̩̤̹̝̬̭͕̟̪̥̈́̀̆͘

Basically if it's not plain text in the language of your reader, it's probably a bad idea.