提交初始版本，使用vant ui库

miniprogram_npm/@vant/weapp/tabbar/index.d.ts

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+export {};

miniprogram_npm/@vant/weapp/tabbar/index.js

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+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+var component_1 = require("../common/component");
+var relation_1 = require("../common/relation");
+var utils_1 = require("../common/utils");
+(0, component_1.VantComponent)({
+    relation: (0, relation_1.useChildren)('tabbar-item', function () {
+        this.updateChildren();
+    }),
+    props: {
+        active: {
+            type: null,
+            observer: 'updateChildren',
+        },
+        activeColor: {
+            type: String,
+            observer: 'updateChildren',
+        },
+        inactiveColor: {
+            type: String,
+            observer: 'updateChildren',
+        },
+        fixed: {
+            type: Boolean,
+            value: true,
+            observer: 'setHeight',
+        },
+        placeholder: {
+            type: Boolean,
+            observer: 'setHeight',
+        },
+        border: {
+            type: Boolean,
+            value: true,
+        },
+        zIndex: {
+            type: Number,
+            value: 1,
+        },
+        safeAreaInsetBottom: {
+            type: Boolean,
+            value: true,
+        },
+    },
+    data: {
+        height: 50,
+    },
+    methods: {
+        updateChildren: function () {
+            var children = this.children;
+            if (!Array.isArray(children) || !children.length) {
+                return;
+            }
+            children.forEach(function (child) { return child.updateFromParent(); });
+        },
+        setHeight: function () {
+            var _this = this;
+            if (!this.data.fixed || !this.data.placeholder) {
+                return;
+            }
+            wx.nextTick(function () {
+                (0, utils_1.getRect)(_this, '.van-tabbar').then(function (res) {
+                    _this.setData({ height: res.height });
+                });
+            });
+        },
+    },
+});

miniprogram_npm/@vant/weapp/tabbar/index.json

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+{
+  "component": true
+}

miniprogram_npm/@vant/weapp/tabbar/index.wxml

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+<wxs src="../wxs/utils.wxs" module="utils" />
+
+<view
+  class="{{ border ? 'van-hairline--top-bottom' : '' }} {{ utils.bem('tabbar', { fixed, safe: safeAreaInsetBottom }) }} custom-class"
+  style="{{ zIndex ? 'z-index: ' + zIndex : '' }}"
+>
+  <slot />
+</view>
+
+<view wx:if="{{ fixed && placeholder }}" style="height: {{ height }}px;"></view>

miniprogram_npm/@vant/weapp/tabbar/index.wxss

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+@import '../common/index.wxss';.van-tabbar{background-color:var(--tabbar-background-color,#fff);box-sizing:initial;display:flex;height:var(--tabbar-height,50px);width:100%}.van-tabbar--fixed{bottom:0;left:0;position:fixed}.van-tabbar--safe{padding-bottom:env(safe-area-inset-bottom)}