1. Data Definition Language (DDL): is responsible for defining database and table including field, data type, length etc.
  2. Data Manipulation Language (DML): is responsible for adding, deleting, updating, looking up data. A more common way to say it is Create, Read, Update, Delete (CRUD)

  1. user login
  2. username/password pass on to the server
  3. server verified the information and grant the permission by sending back the authentication token
  4. once we receive the authentication token, we will use it in every of our user request

setTimeout( () => {console.log('wait for 0 sec')},0)

  1. basic extract

  • Const : block-scoped, much like variables declared using the let keyword. The value of a constant can't be changed through reassignment, and it can't be redeclared.
  • Let: statement declares a block-scoped local variable, optionally initializing it to a value.


Hello, I am Heidi. I started this medium blog to post all of the note I have when I am learning new things. Hope you find it useful as well:)

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