Ebook – JavaScript

The Modern Javascript

  • Types
    • Use “null” to write an “empty” or an “unknown” value into the variable
    • “undefined” is only used for checks, to see if the variable is assigned or not
      • The meaning of undefined is “value is not assigned”
      • If a variable is declared, but not assigned, then its value is exactly undefined
  • Functions
    • Callback functions
    • Function Declaration and Function Expression
    • Arrow Functions

      [js]let sum = (a, b) => a + b;
      alert( sum(1, 2) ); // 3[/js]

      This equals to

      [js]let sum = function(a, b) {
      return a + b;
      };[/js]

      • Multiline Arrow Functions

        [js]let sum = (a, b) => { // the figure bracket opens a multiline function
        let result = a + b;
        return result; // if we use figure brackets, must use return
        };

        alert( sum(1, 2) ); // 3

        [/js]

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