DOM element manipulation in JavaScript

DOM Event actions in JavaScript

• Function

• • The function is to encapsulate some methods by calling the Execute function.
  • Role:
    • Avoid repeating the code.
    • Simplify programming and make programming modular.
  • Syntax: Fuction () {}
    • function is a keyword, similar to the "def" of a function defined in Python;
    • Enclose parameters in parentheses
    • A function statement is placed in curly braces.
  • Call to function
    • Function name + ()
  • parameters of the function
    • parameter
    • argument
  • Argument: can only be used in functions.
    • Number of returned arguments: argument.length
    • Returns the number of formal parameters: Fn.length
    • Pseudo-Array
      • You can modify the element, but you cannot change the length of the array. (Use only the array method)　　　　　　　　　　　　　　

• • • • Empty array
        1. Array.splici (0)
        2. Array.Length = 0
        3. Array = []

• DOM Event action
  • JS is an event-driven core language.

• • Event three elements:　　
    • Event Source: HTML tag that raises subsequent events
    • Event: a drive action
    • Event driver: An action on a style or HTML.

• • Event writing steps

• • • Gets the event source.
      1. Get a single tag by ID :getElementById ("ID name") must be quoted and element has no s.
      2. Get an array of tags by tag name : getElementsByTagName ("tag name"), Elenment has s,
      3. Get label Group BY class name:getelementsbyclassname ("Class name")Elenment has s,　　
    • The binding event.
      1. Directly binds an anonymous function.
      2. Define the function first, and then bind the encapsulated function body.
         • Note: The binding is FN, not FN (), and FN () refers to the function's return value. 　　
      3. In-line methods.
      • • inline style, when you write FN (), you must have parentheses at this point, otherwise parse to a string .

          　　　　　　

    • Write event drivers. Operations on the DOM

• • • • Notes for writing code:
        1. When writing attribute values in JS, use quotation marks.
        2. When writing attributes in JS, write a camel's body, such as backgroundcolor.　　　　　　　　

DOM element manipulation in JavaScript