$\textcolor{red}{\textsf{Compact Caesar Cipher}}$

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GUI Python3 (Jupyter Notebook)

def r_string(s,k): return(''.join([ chr(97+(ord(c)-97+k)%26) for c in s ]))
def F():
    import ipywidgets as widgets
    from ipywidgets import HBox, VBox
    import numpy as np
    import matplotlib.pyplot as plt
    from IPython.display import display
    %matplotlib inline
    @widgets.interact
    def f(BOX=widgets.Text(value='abcdefghijklmnopqrstuvwxyz', disabled=False),k=range(0,26)):
        plain_text = BOX
        print(r_string(BOX,k))
F()

• implementation

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JavaScript (js)

• implementation

function rot(s,i) {return s.replace(/[a-zA-Z]/g, function (c) {  return String.fromCharCode((c <= 'Z' ? 90 : 122) >= (c = c.charCodeAt(0) + i) ? c : c - 26); });}

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