First pass at systime app

content/extras/date/_index.md

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+---
+title: Systime Date Converter
+---
+
+<div id="converter">
+<input type="text" class="systime">
+⇄
+<input type="datetime-local" class="date">
+</div>
+<script src="convert.js"></script>

content/extras/date/convert.ts

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+class Systime {
+    year: number;
+    dayOfYear: number;
+    hundredths: number;
+
+    constructor(date: Date) {
+        this.fromDate(date);
+    }
+
+    fromDate(date: Date): void {
+    }
+
+    toDate(): Date {
+    }
+
+    fromString(str: string): void {
+    }
+
+    toString(): string {
+    }
+};

content/extras/systime.md

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+---
+title: Systime
+---
+
+You can use this form to convert to/from [systime](https://wiki.post-self.ink/wiki/Systime).
+
+<div style="text-align: center;">
+    <input type="text" id="systime" value="systime 1+21" /><br>
+    <input type="button" id="convert" value="Convert systime..." />
+</div>
+<div id="output" />
+<script type="text/javascript">
+    document.getElementById('convert').addEventListener("click", (ev) => {
+        fetch(`https://systime.post-self.ink/api/1/systime/${document.getElementById('systime').value}`)
+            .then((response) => {
+                if (!response.ok) {
+                    document.getElementById('output').innerHTML = `Error converting systime`;
+                    throw new Error(response.status);
+                }
+                return response.json();
+            })
+            .then((json) => {
+                document.getElementById('output').innerHTML = `
+                <dl>
+                    <dt>Systime</dt>
+                    <dd>${json.systime.string}</dd>
+                    <dt>Gregorian</dt>
+                    <dd>${json.gregorian.string}</dd>
+                    <dt>Hebrew</dt>
+                    <dd>${json.hebrew.string}</dd>
+                </dl>`;
+            });
+    });
+</script>
+