Initial commit

2020-06-15 10:58:47 +08:00
commit 4f1dfe7564
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+var _ = require('underscore');
+
+/**
+ * Value object to calcualte distances
+ */
+module.exports = {
+  OPTIONS: [
+    {
+      distance: 'meters',
+      metersPerDistance: 1
+    }, {
+      distance: 'kilometers',
+      metersPerDistance: 1000
+    }, {
+      distance: 'miles',
+      metersPerDistance: 1609.34
+    }
+  ],
+
+  /**
+   * @param {Number} val - e.g. 3
+   * @param {String} distance - e.g. 'kilometers'
+   * @param {Float} e.g. 3000
+   */
+  toMeters: function (val, distance) {
+    val = parseFloat(val);
+    if (isNaN(val)) throw new Error('val (1st arg) is required, expected a parseable number or float');
+
+    var option = _.find(this.OPTIONS, function (d) {
+      return d.distance === distance;
+    });
+    if (!option) throw new Error(distance + ' (2nd arg) is not a valid distance value, expects one of ' + _.pluck(this.OPTIONS, 'distance').join(', '));
+
+    return val * option.metersPerDistance;
+  },
+
+  toDistance: function (meters, distance) {
+    meters = parseFloat(meters);
+    if (isNaN(meters)) throw new Error('meters (1st arg) is required');
+
+    var option = _.find(this.OPTIONS, function (d) {
+      return d.distance === distance;
+    });
+    if (!option) throw new Error(distance + ' (2nd arg) is not a valid distance value, expects one of ' + _.pluck(this.OPTIONS, 'distance').join(', '));
+
+    return meters / option.metersPerDistance;
+  }
+};