主要原因是安装的jquery版本和ztree中的版本不匹配。
1、配置package.json：
"dependencies": {
"axios": "^0.19.2",
"bootstrap": "^3.4.1",
"bootstrap-table": "^1.11.1",
"bootstrap-validator": "^0.11.9",
"bootstrapvalidator": "^0.5.4",
"echarts": "^4.2.1",
"element-ui": "^2.13.2",
"jquery": "^3.3.1",
"popper.js": "^1.16.1",
"vue": "^2.5.2",
"vue-router": "^3.0.1",
"vuex": "^3.1.0",
"ztree": "^3.5.24"
}
2、build/webpack.base.conf.js中配置ProvidePlugin：
module.exports = {
plugins: [
new webpack.ProvidePlugin({
$: "jquery",
jQuery: "jquery",
'window.jQuery': 'jquery',
jQuery: 'jquery'
})
]
}3、main.js中引入ztree：
import 'ztree'
import 'ztree/css/metroStyle/metroStyle.css'