Global Objects
He explained: "reveal the object." It does not belong to any of the properties and methods of other objects, and ultimately its properties and methods. In fact there is no global variables and functions are properties of global object. Including isNaN (), isFinite (), parseInt (), parseFloat (), as well as methods
1.URI coding method
encodeURI()
encodeURIComponent()
Use encodeURIComponent () method more than encodeURI ().
栗子：var uri = "http://www.wrox.com/illegal value.htm#start";
//"http://www.wrox.com/illegal%20value.htm#start "
of nco shed (on)
//"http%3A%2F%2Fwww.wrox.com%2Fillegal%20value.htm%23start"
encodeURIComponent(uri)
2.eval () method
Only accepts one parameter, a string that is to be executed. It will be passed as actual parameters js statement to resolve.
Code is executed may contain references to variables defined in the environment.
You can define a function eval (), and then reference the function in the function of the external code.
In strict mode, not visit eavl (any variable or function) created externally.
Chestnut: eval ( "alert ( 'hi')") is equal to alert ( "hi")
var mes = "hello world"
eval("alert(msg)") //"hello world"
eval("function sayHI(){alert('hi')}")
sayHI ()
3.window objects
In all variables and functions at global declaration space, it has become the property of the window object.
Chestnuts: var color = "red"
function saycolor(){
alert(window.color) //"red"
}
Math object
1.min () and max () method
Means for determining a set of minimum and maximum values in the array. Any number of parameters.
Chestnut: var max = Math.max (3,5,32,16) var min = Math.max (3,5,32,16)
alert (max) 32 // alert (min) // 3
To find an array maximum or minimum value, you can use the apply () method
Chestnut: var values = [1, 2, 3, 4, 5, 6, 7, 8]
var max = Math.max.apply (this, values) // this value of the window, so this can also be written window, Math. In practice this is to change the point of
2. Rounding Method
Math.ceil () rounds up
Math.floor () rounded down
Math.round () rounding
3.random () method of the random number
Math.random () method returns a random number greater than 0 to less than 1.
Chestnut: randomly selecting a value within a range of integers.
Value = Math.floor (Math.random () * + total number of possible values of a possible value)
Such as: 1 to 10 random number directly
var n = Math.floor(Math.random() * 10 + 1)
A random number between 2-10
var m = Math.floor( Math.random() * 9 +2 )
Chestnut: a randomly taken from the array
function select (lower, upper) { // accepts two parameters: minimum and maximum values should return
var chioce = upper - lower +1
return Math.floor( Math.random() * chioce + lower)
}
var num = select (2.10) alert (number);
var colors = ["red", "green", "blue", "yellow", "black", "purple", "brown"];
var color = colors[selectFrom(0, colors.length-1)];
alert(color);
