第五章 引用类型

function compare(value1, value2) {
if (value1 < value2) {
return -1;
} else if (value1 > value2) {
return 1;
} else {
return 0;
}
}
 
var values = [0, 1, 5, 10, 15];
values.sort(compare);
alert(values); //0,1,5,10,15
function compare(value1, value2) {
    return value2-value1;
}

var colors = ["red", "green", "blue"];
var colors2 = colors.concat("yellow", ["black", "brown"]);
 
alert(colors); //red,green,blue
alert(colors2); //red,green,blue,yellow,black,brown

var colors = ["red", "green", "blue", "yellow", "purple"];
var colors2 = colors.slice(1);
var colors3 = colors.slice(1,4);
 
alert(colors2); //green,blue,yellow,purple
alert(colors3); //green,blue,yellow

var colors = ["red", "green", "blue"];
var removed = colors.splice(0,1); //remove the first item
alert(colors); //green,blue
alert(removed); //red - one item array
 
removed = colors.splice(1, 0, "yellow", "orange"); //insert two items at position 1
alert(colors); //green,yellow,orange,blue
alert(removed); //empty array
 
removed = colors.splice(1, 1, "red", "purple"); //insert two values, remove one
alert(colors); //green,red,purple,orange,blue
alert(removed); //yellow - one item array

var numbers = [1,2,3,4,5,4,3,2,1];
 
alert(numbers.indexOf(4)); //3
alert(numbers.lastIndexOf(4)); //5
 
alert(numbers.indexOf(4, 4)); //5
alert(numbers.lastIndexOf(4, 4)); //3
 
var person = { name: "Nicholas" };
var people = [{ name: "Nicholas" }];
var morePeople = [person];
 
alert(people.indexOf(person)); //-1
alert(morePeople.indexOf(person)); //0

var numbers = [1,2,3,4,5,4,3,2,1];
 
var everyResult = numbers.every(function(item, index, array){
return (item > 2);
});
 
alert(everyResult); //false
 
var someResult = numbers.some(function(item, index, array){
return (item > 2);
});
 
alert(someResult); //true
 
var numbers = [1,2,3,4,5,4,3,2,1];
 
var filterResult = numbers.filter(function(item, index, array){
return (item > 2);
});
 
alert(filterResult); //[3,4,5,4,3]
 
var numbers = [1,2,3,4,5,4,3,2,1];
 
var mapResult = numbers.map(function(item, index, array){
return item * 2;
});
 
alert(mapResult); //[2,4,6,8,10,8,6,4,2]

var values = [1,2,3,4,5];
var sum = values.reduce(function(prev, cur, index, array){
    return prev + cur;
});
alert(sum);//15

function createComparisonFunction(propertyName) {
 
return function(object1, object2){
var value1 = object1[propertyName];
var value2 = object2[propertyName];
 
if (value1 < value2){
    return -1;
} else if (value1 > value2){
    return 1;
} else {
    return 0;
}
};
}
 
var data = [{name: "Zachary", age: 28}, {name: "Nicholas", age: 29},{name: "Donghao",age: 23}];
 
data.sort(createComparisonFunction("name"));
alert(data[0].name); //Nicholas
 
data.sort(createComparisonFunction("age"));
alert(data[0].name); //Zachary

function sum(num1, num2){
    return num1 + num2;
}
 
function callSum1(num1, num2){
    return sum.apply(this, arguments);
}
 
function callSum2(num1, num2){
    return sum.apply(this, [num1, num2]);
}
 
alert(callSum1(10,10)); //20
alert(callSum2(10,10)); //20
 
function sum(num1, num2){
    return num1 + num2;
}
 
function callSum(num1, num2){
    return sum.call(this, num1, num2);
}
 
alert(callSum(10,10)); //20

window.color = "red";
var o = { color: "blue" };
 
function sayColor(){
    alert(this.color);
}
 
sayColor(); //red
 
sayColor.call(this); //red
sayColor.call(window); //red
sayColor.call(o); //blue

window.color = "red";
var o = { color: "blue" };
 
function sayColor(){
    alert(this.color);
}
var objectSayColor = sayColor.bind(o);
objectSayColor(); //blue

var falseObject = new Boolean(false);
var result = falseObject && true;
alert(result); //true
 
var falseValue = false;
result = falseValue && true;
alert(result); //false
 
alert(typeof falseObject); //object
alert(typeof falseValue); //boolean
alert(falseObject instanceof Boolean); //true
alert(falseValue instanceof Boolean); //false

var stringValue = "hello world";
alert(stringValue.slice(3)); //"lo world"
alert(stringValue.substring(3)); //"lo world"
alert(stringValue.substr(3)); //"lo world"
alert(stringValue.slice(3, 7)); //"lo w"
alert(stringValue.substring(3,7)); //"lo w"
alert(stringValue.substr(3, 7)); //"lo worl" 第二个参数是长度
 
alert(stringValue.slice(-3)); //"rld"
alert(stringValue.substring(-3)); //"hello world"
alert(stringValue.substr(-3)); //"rld"
alert(stringValue.slice(3, -4)); //"lo w"
alert(stringValue.substring(3, -4)); //"hel"
alert(stringValue.substr(3, -4)); //"" (empty string)

var stringValue = "hello world";
alert(stringValue.indexOf("o")); //4
alert(stringValue.lastIndexOf("o")); //7
alert(stringValue.indexOf("o", 6)); //7
alert(stringValue.lastIndexOf("o", 6)); //4

var text = "cat, bat, sat, fat";
var pattern = /.at/;
 
var matches = text.match(pattern);
alert(matches.index); //0
alert(matches[0]); //"cat"
alert(pattern.lastIndex); //0
 
var pos = text.search(/at/);
alert(pos); //1
 
var result = text.replace("at", "ond");
alert(result); //"cond, bat, sat, fat"
 
result = text.replace(/at/g, "ond");
alert(result); //"cond, bond, sond, fond"
 
result = text.replace(/(.at)/g, "word ($1)");
alert(result); //word (cat), word (bat), word (sat), word (fat)
 
function htmlEscape(text){
return text.replace(/[<>"&]/g, function(match, pos, originalText){
switch(match){
case "<":
return "<";
case ">":
return ">";
case "&":
return "&";
case "\"":
return """;
}
});
}
 
alert(htmlEscape("<p class=\"greeting\">Hello world!</p>")); //<p class="greeting">Hello world!</p>
 
var colorText = "red,blue,green,yellow";
var colors1 = colorText.split(","); //["red", "blue", "green", "yellow"]
var colors2 = colorText.split(",", 2); //["red", "blue"]
var colors3 = colorText.split(/[^\,]+/); //["", ",", ",", ",", ""]

var uri = "http://www.wrox.com/illegal value.htm#start";
 
//"http://www.wrox.com/illegal%20value.htm#start"
alert(encodeURI(uri));
 
//"http%3A%2F%2Fwww.wrox.com%2Fillegal%20value.htm%23start"
alert(encodeURIComponent(uri));
 
var uri = "http%3A%2F%2Fwww.wrox.com%2Fillegal%20value.htm%23start";
 
//http%3A%2F%2Fwww.wrox.com%2Fillegal value.htm%23start
alert(decodeURI(uri));
 
//http://www.wrox.com/illegal value.htm#start
alert(decodeURIComponent(uri));

var num = Math.floor(Math.random() * 10 + 1);//1到10间的数
 
var num = Math.floor(Math.random() * 9 + 2);//2到11间的数