move misc to js/ui

1-js/99-js-misc/02-eval/1-eval-calculator/solution.md

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+Let's use `eval` to calculate the maths expression:
+
+```js demo run
+let expr = prompt("Type an arithmetic expression?", '2*3+2');
+
+alert( eval(expr) );
+```
+
+The user can input any text or code though.
+
+To make things safe, and limit it to arithmetics only, we can check the `expr` using a [regular expression](info:regular-expressions), so that it only may contain digits and operators.

1-js/99-js-misc/02-eval/1-eval-calculator/task.md

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+importance: 4
+
+---
+
+# Eval-calculator
+
+Create a calculator that prompts for an arithmetic expression and returns its result.
+
+There's no need to check the expression for correctness in this task.
+
+[demo]