feat: add reverse-polish-notation javascript solution

.gitignore

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 node_modules
-.vscode
+.vscode
+.theia

challenges/reverse-polish-notation/solutions/javascript-solution/README.md

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+# javascript-solution - reverse-polish-notation
+
+Programming language : JavaScript
+
+Created by [@Divlo](https://github.com/Divlo) on 29 September 2020.

challenges/reverse-polish-notation/solutions/javascript-solution/solution.js

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+const operations = {
+  '+': (n1, n2) => n1 + n2,
+  '-': (n1, n2) => n1 - n2,
+  '*': (n1, n2) => n1 * n2,
+  '/': (n1, n2) => n1 / n2
+}
+
+function solution(value) {
+  if (value.length === 0) {
+    return 0
+  }
+
+  const stack = []
+  const values = value.split(' ')
+  values.forEach((value) => {
+    const number = Number(value)
+    if (!isNaN(number)) {
+      stack.push(number)
+    } else if (operations.hasOwnProperty(value)) {
+      const number1 = stack.pop()
+      const number2 = stack.pop()
+      const operation = operations[value]
+      const result = operation(number2, number1)
+      stack.push(result)
+    }
+  })
+
+  return stack.pop()
+}
+
+module.exports = solution