switch Statements of ECMAScript

switch 语句

switch 语句 ni yin yi 'brother' of if 语句.

开发者 can use switch 语句 to provide a series of cases (case) for expressions.

语法 of switch 语句：

switch (expression)
  case value: statement;
    break;
  case value: statement;
    break;
  case value: statement;
    break;
  case value: statement;
    break;
...
  case value: statement;
    break;
  default: statement;

kowane dake (case) ni yin yi 'kif expression kuma yake daidai value，daga baya a gudanar statement。

Kananan hanyar break yana samun hanyar kisan kiyashi daga hanyar switch. Bugu da kari kananan hanyar break, hanyar yana gudanar da kisan kiyashi a cikin hanyar na kowace case.

Kananan hanyar default yana bayyana a cikin wani hanyar cewa jumladan hanyar ba a samu wariyar wuri kowace kuma yana da matsakaici kuma yana da matsakaici da hanyar else.

Hanyar switch ana amfani dashi domin kare da kisan kiyashi a cikin kisan kiyashi na wasa na yawa:

if (i == 20)
  alert("20");
else if (i == 30)
  alert("30");
else if (i == 40)
  alert("40");
else
  alert("other");

Hanyar switch da ke da hanyar da yake daidai shine:

switch (i) {
  case 20: alert("20");
    break;
  case 30: alert("30");
    break;
  case 40: alert("40");
    break;
  default: alert("other");
}

Hanyar switch a ECMAScript da Java

Hanyar switch a ECMAScript da Java ke da wa'adi biyu. A ECMAScript, hanyar switch za a iya amfani da jine, kuma za a iya bayyana dalilai da yake yin hanyar kuma ba shi da shi ne shi ne kamar shi ne:

var BLUE = "blue", RED = "red", GREEN = "green";
switch (sColor) {
  case BLUE: alert("Blue");
    break;
  case RED: alert("Red");
    break;
  case GREEN: alert("Green");
    break;
  default: alert("Other");
}

Hicci, hanyar switch ke amfani da jine sColor, yana bayyana case a yau ne Blue, RED da GREEN, wanda a ECMAScript ya zama a cikin shawarar.