"Practice" javascript some exercises summarize, thinking model

1 Write a method () to determine whether a number can be divisible by 3 and 5 at the same time

<script type= "Text/javascript" >functionmethod () {varnum = Prompt ("Enter a number"); if(IsNaN (num)) {return""; }   //this verifies that the input is not a number, and if it does not enter isNaN, then return ' will exit the function        if(+num% 3 = = 0 && +num% 5 ==0) {document.write (num+ "can be divisible by 3 and 5"); }Else{document.write (num+ "cannot be divisible by 3 and 5")}} method ()//calling Functions</script>

2 Write a Method GetValue (), on any parameter x, returns the value of Y; x<1, when Y;10>x>1 is returned, y=2*x-1;x>10, y=3*x-11

<script type= "Text/javascript" >functionget () {varx = document.getElementById ("in1"). Value,//gets the value of the in1, which is the values entered xy = 0; if(+x < 1) {y=x; }Else if(+x >= 1 && +x < 10) {y= (+x)-1; }Else if(+x > 10) {y= 11 (+x); } document.getElementById ("In2"). Value =y;//Gets the value of in2 and assigns the y of the operation pair to in2, so that the number of calculations will appear in the input of in2    }</script>Enter a number:<input id= "in1" type= "text" onblur= "Get ()" Value= "" ><br>//OnBlur lose Focus buttonThe value of calculated y is <input type= "tel" value= "" id= "in2" ></body>

3 Implement a simple calculator, enter two numbers and an operation symbol, calculate the result. The calculation process uses a parametric and return-worthy function encapsulation implementation

    functionMethod (a,b,c) {//Judging if A and B are numbers .        if(IsNaN (a) | |IsNaN (b)) {            return"Please enter the correct word";//isNaN judgment is not a number if it is not entered if function, and Returun returns the value "、、、、"        }        if(["+", "-", "*", "/"].indexof (c) = =-1) {//Idndexof () is the array subscript, if C is in the array, is to return the corresponding subscript, the smallest is 0, if =-1, indicating there is no            return"Please enter the correct (subtraction)"; }        varNum =eval (A+C+B);//evaluates the result and returns a result        returnnum; }    functionJisuan () {//The first step gets the input numbers and symbols        varA =document.getelementbyid ("one"). Value, b=document.getelementbyid ("the"). Value, C=document.getelementbyid ("FH"). Value; //The function method is called, and the returned value is received        varnum =method (A,B,C); document.getElementById ("JG"). innerhtml=num; }    </script>Number 1:<input type= "text" id= "one" ><br>Number 2:<input type= "text" id= "both" ><br>Symbols:<input type= "text" id= "FH" ><br><button onclick= "Jisuan ()" > Calculation </button> Result: <span id= "JG" ></span>

4 Full selection/All-in-one effect. If the check box below is not selected, the Select all check box is automatically unchecked and checked automatically if all

<script type= "Text/javascript" >//Select All/ Select all    /*1. Find All box 2, get all marquee Check Property 3, get all the checkbox element 4, set the check attribute of these checkbox elements to the Check property of the Select box*/        functionCheck (obj) {//1. Find all Boxes//2. Get all marquee Check Properties//3. Get all the checkbox elements        varCkarr = document.getelementsbyname ("list"); //4. Set the check attribute of these checkbox elements to the selected property of the Select All box         for(vari = 0; i<ckarr.length;i++){            if(obj.checked) {//ckarr[i].setattribute ("Checked", "checked");ckarr[i].checked =true; }Else{        //ckarr[i].removeattribute ("checked");ckarr[i].checked =false; }                    }    }        /*1, get all the checkbox element 2, each to determine whether to select 3, if there is no selected check box unchecked and select*/    </script>varCkarr = document.getelementsbyname ("list");  for(vari = 0; i<ckarr.length;i++) {Ckarr[i].setattribute ("onclick", "Isxz ()"); }        functionIsxz () {//1. Get all checkbox elements        varFlag =true; //2, each judge whether to select         for(vari = 0; i<ckarr.length;i++){            if(!ckarr[i].checked) {Flag=false; }        }    //3, if there is no check box selected uncheck the Reverse selection        //flag = true; Select All        //flag = false; Are there any selected        if(flag) {document.getElementById ("QX"). Checked =true; }Else{document.getElementById ("QX"). Checked =false; }    }</script>

"Practice" javascript some exercises summarize, thinking model