The problem of using axios under vue

beginners, chrome appears

when using axios to process return values
TypeError: Cannot set property "menu" of undefined

error, I don"t know why. The
menu variable I have defined in data.
use mockjs to intercept.
axios part of the code is as follows
clipboard.png
response.data.menuconsole
axiosmenu2this.menu
clipboard.png
menu2mockjs
chromeconsole:
clipboard.png

clipboard.png
I don"t know why

Mock.js axios vue.js
Mar.10,2021 
then(function(response){
    this.menu =....
})
Change

to 

then(response => {
    this.menu =....
})

returns a string, and the return type needs to be specified as json

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MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1eb3c59-2481.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1eb3c59-2481.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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