JS Review Basic grammar

Pop-up window:

　　Alret ("What to Eject"); Don't make sure the page doesn't go down after it pops up.

　　Confirm ("What to Eject"); OK dialog box, click OK to return True, point cancel returns false, available variables accept

　Prompt ("Hint text to display"); pops up a dialog box that allows you to enter content

Prompt ("Lose a number come in", "can only be a number");

　　

Basic syntax

Basically consistent with C # syntax

break; jump out of the current loop

Continue; skip this cycle

Type conversions

　　　var a=parseint (value), other types converted to integers

var a=parsefloat (value), other types converted to integers

IsNaN (value); Determines whether a valid number is returned true is not a return false

　　　　　　

<script>    var  A;    Prompt (" lose a number come in "" can only be a number oh ");     = IsNaN (); // put the input into isNaN ()    alert (a); // if it is a numeric bullet true, it is not a digital bomb false</script>

Four forms of the function (no specified type)

No parameter no return value

  test1 ();    function Test1 () {        alert ('hello');    }

No parameter has return value

There are no return values for parameters

<script>    test1 (5,6);    function Test1 (A, b) {        alert ('a+b');    } </script>

There are parameters with return values

<script>    var ccc = test1 (56);    Alert (CCC);    function Test1 (A, b) {        var c = a + b;         return c;    } </script>

JS Review Basic grammar