From 753135c8b209f9c49f525e0814340575c47115ff Mon Sep 17 00:00:00 2001
From: aozhiwei <aozhiwei@kingsome.cn>
Date: Wed, 21 Sep 2022 19:30:19 +0800
Subject: [PATCH] 1

---
 utils.js | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/utils.js b/utils.js
index 07b9fb4..bb95454 100644
--- a/utils.js
+++ b/utils.js
@@ -251,6 +251,36 @@ function isPureNumberStr(str) {
   return true;
 }
 
+function randItemByWeight(list, fieldName) {
+  const ret = {
+    'index': -1,
+    'item': null
+  };
+  let totalSpace = function () {
+    let space = 0;
+    list.forEach((item) => {
+      space += Number(item[fieldName]);
+    });
+    return space;
+  }();
+  if (totalSpace > 0) {
+    const rand = randRange(0, totalSpace - 1);
+    let currSpace = 0;
+    for (let i = 0; i < list.length; ++i) {
+      currSpace += Number(list[i][fieldName]);
+      //console.log(currSpace, rand, totalSpace, list);
+      if (rand < currSpace) {
+        ret['index'] = i;
+        ret['item'] = list[i];
+        break;
+      }
+    }
+  } else {
+    console.log('randItemByWeight error:', list);
+  }
+  return ret;
+}
+
 exports.rspErr = rspErr;
 exports.rspOk = rspOk;
 exports.rspData = rspData;
@@ -266,6 +296,7 @@ exports.getHourSeconds = getHourSeconds;
 exports.formatDate = formatDate;
 exports.pad = pad;
 exports.randRange = randRange;
+exports.randItemByWeight = randItemByWeight;
 exports.jsonEncode = jsonEncode;
 exports.prettyJsonEncode = prettyJsonEncode;
 exports.jsonDecode = jsonDecode;