JavaScript function call classic example code

JavaScript function call classic example
Definition and calling method of JS function
Summarize

JavaScript function call classic example

1. Input box to determine whether it is a leap year

2. Random number to determine whether it is a leap year

3. Input box determines whether it is a prime number

4. Determine whether a random number is prime

5. Encapsulate the function to determine whether the date is legal

Thinking: First, we use the function calling method and write all the functions to be called in the js folder, which will be more convenient when calling. It is important to note that do not forget to introduce js in HTML.

HTML code:

<body>
    <span>Is it a leap year?</span>
    <input type="text" id='inp1'>
    <br>
    <span>Is it a prime number?</span>
    <input type="text" id="inp2">
    <br>

    <!-- Externally import js files-->
    <script src="../js/tools_practice.js"></script>

    <script>
        //Call the object acquisition function var oInp1 = get('inp1');

        //Determine whether it is a leap year var year = leap_year(2004);
        
        //Assign value to input box if(year){
            oInp1.value = 'It is a leap year';
        }
        else{
            oInp1.value = 'Not a leap year';
        }

        //Call a random number to generate a year and determine whether it is a leap year var y = rand(1000, 2000);
        var res = leap_year(y);
        if(res){
            document.write('random number' + y + 'is a leap year' + '&nbsp;&nbsp;&nbsp;&nbsp;');
        }
        else{
            document.write('random number' + y + 'not a leap year' + '&nbsp;&nbsp;&nbsp;&nbsp;');
        }



        //Call function to get related objects var oInp2 = get('inp2');

        //Input box determines whether it is a prime number var n = isZhi(14);

        //Assign value to the prime number input box if(n){
            oInp2.value = 'is a prime number'
        }
        else{
            oInp2.value = 'Not a prime number'
        }

        //Call a random number to generate a number and determine whether it is a prime number var num = rand(0,1000);
        var res3 = isZhi(num);
        if(res3){
            document.write('random number' + num + 'is a prime number' + '&nbsp;&nbsp;&nbsp;&nbsp;');
        }
        else{
            document.write('random number' + num + 'not a prime number' + '&nbsp;&nbsp;&nbsp;&nbsp;');
        }


        //Encapsulation function to determine whether the date is legal var da = data(1233,1,32);
        if(da){
            document.write('Legal date' + '&nbsp;&nbsp;&nbsp;&nbsp;');
        }
        else{
            document.write('The date is illegal' + '&nbsp;&nbsp;&nbsp;&nbsp;');
        }

    </script>
</body>

js code:

//Function: Determine whether a year is a leap year//Parameters:
//number
//Return value:
// boolean
function leap_year(x) {
    if (x % 4 === 0 && x % 100 !== 0 || x % 400 === 0) {
        return true;
    }
    return false;
}

//Get the object function get(id) {
    return document.getElementById(id);
}

//Function: Generate a random integer within a certain range //Parameters:
// min number range minimum value // max number range maximum value // return value:
//number
function rand(min, max) {
    return Math.round(Math.random() * (max - min) + min);
}

//Function: Determine whether a number is prime//Parameters:
//number
//Return value:
// boolean
function isZhi(n) {
    for (var i = 2; i < n; i++) {
        if (n % i === 0) {
            return false;
        }
    }
    return true;
}

//Function: Determine whether the date is legal//Parameters:
// y number year // m number month // d number date // return value:
// boolean
function data(y, m, d) {
    //First determine the year --> then determine the month --> then determine the date //Determine the year:
    if (y >= 1000 && y <= 2000 && y % 1 === 0) {
        //Judge the monthif (m >= 1 && m <= 12 && m % 1 === 0) {
            var maxDay;
            if (m === 1 || m === 3 || m === 5 || m === 7 || m === 8 || m === 10 || m === 12) {
                maxDay = 31;
            }
            else if (m === 4 || m === 6 || m === 9 || m === 11) {
                maxDay = 30;
            }
            else if (m === 2) {
                if (y % 4 === 0 && y % 100 != 0 || y % 400 === 0) {
                    maxDay = 29;
                }
                else {
                    maxDay = 28;
                }
            }
            //Judge the date if(d >= 1 && d <= maxDay && d % 1 === 0){
                return true ;
            }
        }
    }
    return false ;
}

Definition and calling method of JS function

Four methods of JS function calling: method calling mode, function calling mode, constructor calling mode, apply, call calling mode

1. Method calling mode:

First define an object, then define the method in the object's properties, and execute the method through myobject.property. this refers to the current myobject object.

var blogInfo={

  blogId:123,

  blogName:"werwr",

  showBlog:function(){alert(this.blogId);}

};



blogInfo.showBlog();

2. Function call mode

Define a function and set a variable name to save the function. At this time, this points to the window object.

var myfunc = function(a,b){
  return a+b;
}

alert(myfunc(3,4));

3. Constructor call mode

Define a function object, define properties in the object, and define methods in its prototype object. When using the prototype method, the object must be instantiated before its method can be called.

var myfunc = function(a){
  this.a = a;
};

myfunc.prototype = {
  show:function(){alert(this.a);}
}

var newfunc = new myfunc("123123123");
newfunc.show();

4.apply, call mode

var myobject={};
var sum = function(a,b){
  return a+b;
};

var sum2 = sum.call(myobject,10,30); //var sum2 = sum.apply(myobject,[10,30]); 

alert(sum2);

Summarize

This is the end of this article about JavaScript function calls. For more relevant JavaScript function calls, please search for previous articles on 123WORDPRESS.COM or continue to browse the following related articles. I hope you will support 123WORDPRESS.COM in the future!

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