js object declaration

One: javascript object

1. Object-based operation (object-oriented encapsulation, inheritance, polymorphism)

2. Use an object to complete related operations as a whole

String Object; Book Order Object; Array; Time Object

the content of the object

1: attribute (variable)

2: Method (function)

are related to this object

1: Declare the object

2: Use objects

3: Using System Objects

step:

1: find the object

2: Instantiate the object

3: Operation object

object instance. property (cancel, assign)

object instance ["attribute name"]

object instance.method()

custom object

    var dt=new Date();
    var str="今天是：";
    str+=dt.getFullYear()+"年";
    str+=(dt.getMonth()+1)+"月";
    str+=dt.getDay()+"日";
    str+=dt.getHours()+":";
    str+=dt.getMinutes()+":";
     str += dt . getSeconds ()+ "week" ;

    switch (dt.getDay()){
        case 0:
            str+="日";
            break;
        case 1:
            str+"一";
            break;
        case 2:
            str+"二";
            break;
        case 3:
            str+"三";
            break;
        case 4:
            str+"四";
            break;
        case 5:
            str+"五";
            break;
        case 6:
            str+"六";
            break;
    }
    document.write(str);

Two: functions in javascript

Function: is a "named" piece of code that performs a specified function.

Functions can only be used by calling, calling: by name (either before or after declaration)

test(); //value

function test(a,b){

Function segment (one, or more)

return value

javascript is object based (everything is the use of objects)

}

test();

1: function name

2: Parameters: Use parameters as needed

3: Function body (function)

4: return value

If the function name does not add (), the function name represents the entire function

Callback

condition:

1. The role of the function decides whether I use it or not

2. The parameters of the function determine how I use it

3. The return value determines how my call number is handled

Three: binary search

<html>
<script>
function binary_search(arr,low,high,key){
if(low>high){
return -1;
}
var mid=parseInt((high+low)/2); //查找结束判定条件
if(arr[mid]==key){
return mid;
}else if(arr[mid]>key){
high=mid-1;
return binary_search(arr,low,high,key);
}else if(arr[mid]<key){
low=mid+1;
return binary_search(arr,low,high,key);
}
};
var arr=[1,2,3,4,5,6,7,8,9,10,11,23,44,86];
var result=binary_search(arr,0,13,10);
alert(result);
</script>
</html>

js object declaration

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