JavaScript Tutorial/Statement/If
Содержание
Conditionals
The format of a simple if statement looks like the following:
<source lang="javascript">
if (expression)
statement;</source>
if...else
Syntax
<source lang="javascript">
if(statement){
code;
}else(statement){
code;
}</source>
if...then...else...if
<source lang="javascript">
<html> <head> <title>if...then...else...if</title> <script type="text/javascript"> var stateCode = "MO"; if (stateCode == "OR") {
taxPercentage = 3.5;
} else if (stateCode == "CA") {
taxPercentage = 5.0;
} else if (stateCode == "MO") {
taxPercentage = 1.0;
} else {
taxPercentage = 2.0;
} document.write(taxPercentage); </script> </head> <body> </body> </html></source>
Nested if statement
<source lang="javascript">
<html> <head> <title>Nested if statement</title> <script> var temp = 0; temp = Math.floor(Math.random() * 100) + 1; alert ("It"s " + temp + " degrees outside. "); if (temp < 70){
if (temp < 30){
alert("< 30");
} else {
alert(" between 30 and 70");
}
} else {
if (temp > 85){
alert("> 85");
} else {
alert("between 85 and 70");
}
} </script> </head> <body>
Hit Reload to see another temperature
</body> </html></source>
Use if/else to check the returning value from a confirm dialog
<source lang="javascript">
<html> <head> <title>A Simple Page</title> <script language="JavaScript">
</script> </head> <body> </body> </html></source>
Use if statement to check the returning value from a confirm dialog
<source lang="javascript">
<html> <head> <title>A Simple Page</title> <script language="JavaScript">
</script> </head> <body> </body> </html></source>
Use if statement to compare the numbers
<source lang="javascript">
<html> <head> <title>Use if statement to compare the numbers</title> <script> var temp = 0; var perfectTemp = 65;
temp = Math.floor(Math.random() * 100) + 1; alert ("It"s " + temp + " degrees outside. "); if (temp < perfectTemp){
alert("Low!!");
} </script> </head> <body>
Hit Reload to see another temperature
</body> </html></source>
