Switch statement skills

Overview

The switch statement evaluates an expression, compares the result with the case substatement, and if it matches, executes downward from the statement at case.

grammar

The break; statement is optional, and if you encounter break; the entire switch statement will pop up. If there is no case match, it goes to the branch of default:. default: The branch is also optional.

switch (expression) {
case value1:
// When the result of expression matches value1, start execution from herestatements1；
[break;]
case value2:
// When the result of expression matches value2, start execution from herestatements2;
[break;]
...
case valueN:
// When the result of expression matches valueN, start execution from herestatementsN;
[break;]
default:
// If expression does not match the value above, execute the statement herestatements_def;
[break;]
}

Use condition judgment in case

Look at the code below, when foo is 0, 1, 2, 3, it shows alert.

var foo = 1;
switch (foo) {
case 0:
case 1:
case 2:
case 3:
alert('yes');
break;
default:
alert('not');
}

Is there a better way to write it? The following is obviously more concise and clear.

var foo = 1;
switch (true) { // Non-variable TRUE replaces foocase foo &gt;= 0 &amp;&amp; foo &lt;= 3:
alert('yes');
break;
default:
alert('not');
}

Indicates a level

The carefully designed switch puts the least rarest conditions on top and the ordinary conditions on the lower side

function rankProgrammer(rank){ 
switch(rank){ 
case "advanced": 
 = true;
case "intermediate": 
 = true;
 = true;
case "primary": 
 = true;
 = true; 
}
}
var xiaohu=new rankProgrammer("advanced");
(xiaohu);

The above content introduces the skills of switch statements to you, and I hope it will help you.