tool to read any day tetris piece

docs/main.js

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+/* exported app, utils */
+
+images = ['piece0_0', 'piece0_1',
+  'piece1_0', 'piece1_1',
+  'piece2_0', 'piece2_1', 'piece2_2', 'piece2_3',
+  'piece3_0', 'piece3_1', 'piece3_2', 'piece3_3',
+  'piece4_0', 'piece4_1',
+  'piece5_0',
+  'piece6_0', 'piece6_1', 'piece6_2', 'piece6_3'];
+
+let app = {
+  el: '#app',
+  data: {
+    title: 'Watchy tools',
+    tetris_input: '',
+    tetris_path: 'img/piece0_0.png'
+  },
+  methods: {
+    compute_tetris: function() {
+      const self = this;
+      const date = new Date(self.tetris_input);
+      const v = Math.floor(self.random_cpp(date) * images.length);
+      self.tetris_path = `img/${images[v]}.png`;
+    },
+    random_cpp: function (date) {
+      let seed = date.getFullYear() - 1970;
+      seed = seed * 12 + (date.getMonth() + 1);
+      seed = seed * 31 + date.getDate();
+    
+      let v = Math.pow(seed, 6/7);
+      v *= (Math.sin(v) + 1);
+    
+      return v - Math.floor(v);
+    },
+  },
+  watch: {
+    tetris_input: 'compute_tetris',
+  },
+  'mounted': function () {
+    const self = this;
+    console.log('app mounted');
+    setTimeout(() => {
+      self.$el.setAttribute('style', '');
+    });
+    self.tetris_input = (new Date()).toISOString().substr(0, 10);
+  }
+};
+
+window.onload = () => {
+  app = new Vue(app);
+};