2.6 KiB
2.6 KiB
id | title | challengeType | videoUrl | forumTopicId | dashedName |
---|---|---|---|---|---|
56533eb9ac21ba0edf2244e0 | 用一个 Switch 语句来替代多个 if else 语句 | 1 | https://scrimba.com/c/c3JE8fy | 18266 | replacing-if-else-chains-with-switch |
--description--
如果你有多个选项需要选择,switch
语句写起来会比多个串联的 if
/else if
语句容易些。 譬如:
if (val === 1) {
answer = "a";
} else if (val === 2) {
answer = "b";
} else {
answer = "c";
}
可以被下面替代:
switch (val) {
case 1:
answer = "a";
break;
case 2:
answer = "b";
break;
default:
answer = "c";
}
--instructions--
把串联的 if
/else if
语句改成 switch
语句。
--hints--
不要使用 else
表达式。
assert(!/else/g.test(code));
不要使用 if
表达式。
assert(!/if/g.test(code));
你应该有至少 4 个 break
表达式。
assert(code.match(/break/g).length >= 4);
chainToSwitch("bob")
应该是字符串 Marley
assert(chainToSwitch('bob') === 'Marley');
chainToSwitch(42)
应该是字符串 The Answer
assert(chainToSwitch(42) === 'The Answer');
chainToSwitch(1)
应该是字符串 There is no #1
assert(chainToSwitch(1) === 'There is no #1');
chainToSwitch(99)
应该为 Missed me by this much!
。
assert(chainToSwitch(99) === 'Missed me by this much!');
chainToSwitch(7)
应该是字符串 Ate Nine
assert(chainToSwitch(7) === 'Ate Nine');
chainToSwitch("John")
应该为 ""
(empty string)。
assert(chainToSwitch('John') === '');
chainToSwitch(156)
应该为 ""
(empty string)。
assert(chainToSwitch(156) === '');
--seed--
--seed-contents--
function chainToSwitch(val) {
let answer = "";
// Only change code below this line
if (val === "bob") {
answer = "Marley";
} else if (val === 42) {
answer = "The Answer";
} else if (val === 1) {
answer = "There is no #1";
} else if (val === 99) {
answer = "Missed me by this much!";
} else if (val === 7) {
answer = "Ate Nine";
}
// Only change code above this line
return answer;
}
chainToSwitch(7);
--solutions--
function chainToSwitch(val) {
let answer = "";
switch (val) {
case "bob":
answer = "Marley";
break;
case 42:
answer = "The Answer";
break;
case 1:
answer = "There is no #1";
break;
case 99:
answer = "Missed me by this much!";
break;
case 7:
answer = "Ate Nine";
}
return answer;
}