JavaScript Process Control Statements-loops

First, the Process Control statement (if statement) in JS

Format:

if ( condition 1) {

if condition 1 is established, execute the code here

}Else{

if the condition is not true , execute the code here

}

format :

if ( condition 1) {

if condition 1 is established, execute the code here

}else if( condition 2) {

if Condition 2 is established, execute the code here

}else if( condition 3) {

If Condition 3 is established, execute the code here

}..........

Else {

if condition 1 to condition n is not true, execute the code here

}

Nested formats:

if ( condition 1) {

if ( condition ) {

if the condition is true , execute the code here

}

}Else{

if condition 1 is not true, execute the code here

}

/*If statement if (condition 1 is true) {if condition 1 is set up, execute the code here}else{if the condition is not true, execute the code here}*/varNUM1 = 10;varnum2 = 20;if(NUM1&LT;NUM2) {//Ten <Alert ("NUM1");}Else{alert ("Num2");} Multiple selection notationvarstr = "3";if(str== "1") {alert ("1");}Else if(str== "2") {alert ("2");}Else if(str== "3") {alert ("3");// here, here.}Else{alert ("6");}//If statement nestingvarnum = 10;varstr = "20";if(num = = 10 ){    if(str== "20") {alert ("True I popped in here"); }}Else{alert ("False, I'm here.");}

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JS in the system input box

prompt () //System input Box

IsNaN ()://Check whether it is a digital

if IsNaN (Ten) writes that the number returns false

if IsNaN ("haha") does not write a number to return the result to True

//1 "If you enter a 100 hint: out of//2 "greater than or equal to 60 hint: pass//3 "Less than or equal to 59 hint: failedvarstr = prompt ("Judging if your grades meet the requirements");if(IsNaN (str)) {alert ("Number must be entered");}Else if(str==100) {alert (Out);}Else if(str>=60| | Str<=99>) {alert (Failed);}Else if(str<=59) {alert ("Failed");}

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JS in the Process Control statement (switch statement)

Format:

Switch ( conditional expression ) {

Case Constants 1:

implementation ;

Break

Case Constants 2:

implementation ;

Break

Case Constants 3:

implementation ;

Break

......

Default

Perform

}

/*if (condition 1) {1 satisfies execution}else if (condition 2) {2 satisfies execution}else{If none is satisfied, execute;}*/varstr = "2";Switch(str) { Case"1": Alert ("1");  Break;  Case"2": Alert ("2");//I'm doing it here .         Break;  Case"3": Alert ("3");  Break; default: Alert ("Neither satisfies execution: default");}

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Second, the Loop statement in JS (for Loop)

Looping statements: In a limited number of conditions, repeated execution of some things

for Loop Format:

for ( starting condition ; Termination Conditions ; Step Value ){

circulation body ;

}

 for (var i=1;i<=100;i++) {    document.write (i+ "<br/>");}

Nested for loop statements in JS

Format:

for ( starting condition ; Termination Conditions ; Step Value ){

for ( starting condition ; Termination Conditions ; Step Value ){

circulation body ;

}

circulation body ;

}

Nested Statements for(vari=0;i<=3;i++) {//0 1 2 3     for(varj=1;j<5;j++) {//1 2 3 4document.write (J+ "<br/>"); }    //document.write (i+ "<br/>");}//2 "3 6 9 12 15 18 .... The remainder of the 3 i%2==0/*For (Var i=1;i<=100;i++) {if (i%3==0) {document.write (i+ "<br/>"); }//document.write (i+ "<br/>");}*///1 "from 1 to 100 numbers//2 "2 4 6 8 10 ... The remainder of the 2 i%2==0 for(vari=1;i<=100;i++){    if(i%10==0) {document.write (i+ "<br/>"); }} multiplication Table small demo//I=1 j=1 j<i+1 that is j<2 cycle once 1*1//i=2 j=1 j<i+1 that is j<3 cycle two times 1*2 2*2//i=3 j=1 j<i+1 namely J<4 cycle three times 1*3 2*3 3*3//i=9 j=1 j<i+1 is j<10 that cycle nine times 1*9 ..... 9*9 for(vari=1;i<=9;i++){        for(varj=1;j<i+1;j++) {document.write (J+ "*" +i + "=" +j*i+ "&nbsp;&nbsp;&nbsp;"    ); } document.write ("<br/>");}

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............ Add

JavaScript Process Control Statements-loops