ECMAScript function overview

Kuwa shafin?

Shafin za a yi wata yankin aiki a kowace lokaci.

Shafin za a yi core ECMAScript.

Shafin za a yi shafin baya kan wannan sabonin: keyword function, sunan shafin, gurin manyan gaba, kuma code na aiki a cikin gaba.

Yanar shafin shafin shafin shafin na:

function functionName(arg0, arg1, ... argN) {
  statements
}

Masanin:

function sayHi(sName, sMessage) {
  alert("Hello " + sName + sMessage);
}

Kuwa za a taama shafin?

Shafin za a za a taama shafin baya kan sunan shafin kan sauki, kuma za a yi aiki tare da manyan gaba.

Iyali kowa ba za a taama shafin gabanin kan shafin, za a iya taama shafin koda na:

sayHi("David", " Nice to meet you!")

Tama shafin gabanin kan shafin sayHi() za a yi fariya ce. An za a亲自试一试这个例子。

函数如何返回值？

函数 sayHi() 未返回值，不过不必专门声明它（像在 Java 中使用 void 那样）。

即使函数确实有值，也不必明确地声明它。该函数只需要使用 return 运算符后跟要返回的值即可。

function sum(iNum1, iNum2) {
  return iNum1 + iNum2;
}

Dabirin a baya yana kai amfani da hanyar a baya don kai amfani da hanyar a baya.

var iResult = sum(1,1);
alert(iResult);	//Babban "2"

Dabirin yana da mahimmanci, kamar yadda a kai amfani da Java, hanyar a baya ita ce kai amfani da hanyar a baya, kuma kowane hanyar a baya a kai amfani da ayyukan hanyar a baya.

Masanin: Idan a kai amfani da hanyar a baya, a kai amfani da wariyar kaiwa ne.

function sum(iNum1, iNum2) {
  return iNum1 + iNum2;
  alert(iNum1 + iNum2);
}

Kamfaniyar hanyar a baya ita ce kai amfani da abin da a baya, kamar yadda a kai amfani da yadda.

function diff(iNum1, iNum2) {
  if (iNum1 > iNum2) {
    return iNum1 - iNum2;
  }
    return iNum2 - iNum1;
  }
}

Hanyar a baya ita ce kai amfani da abin da a baya don kai amfani da abin da a baya, don haka a kai amfani da dabirin if don kai amfani da hanyar a baya.

Idan hanyar a baya ba a koyar da aiki, a kai amfani da hanyar a baya da ba a haɗa da abin da a baya ba, kai tsaye a iya kai ayyukan hanyar.

Masanin:

function sayHi(sMessage) {
  if (sMessage == "bye") {
    return;
  }
  alert(sMessage);
}

Idan sMessage kuma yana da "bye", a kai amfani da wariyar kaiwa ne.

Rarrabuwa:Idan hanyar a baya ba a bayyana hanyar a bayan yin aiki, ko an yi amfani da hanyar a baya da ba a haɗa da abin da a baya ba, kamannin hanyar a baya ta kasance undefined.