JavaScript fannin yai kiki

Tirin da koyi da koyi

fannin yai kiki fannin gaskiya, kada daceen yai fannin kiki yai kai.

Kada daceen yai, fannin kiki yai kai. Kada daceen yai yai, fannin kiki yai kai.

JavaScript yancin gaskiya fannin kiki:

  • for - fannin kiki
  • for/in - yin fannin gaskiya kiki
  • for/of - 循环遍历可迭代对象的值
  • while - 在指定条件为真时循环代码块
  • do/while - 循环一次代码块，然后在指定条件为真时重复循环

提示：请使用 break 语句跳出循环，使用 continue 语句跳过循环中的某个值。

Ɗakarun

循环代码块五次：

var text = "";
var i;
for (i = 0; i < 5; i++) {
  text += "The number is " + i + "<br>";
{}

Ɗaɗaɗan Ɗaɗaɗa

页面下方有更多 TIY 实例。

语法

for (statement 1; statement 2; statement 3) {
  code block to be executed
{}

参数值

参数 描述
statement1

可选。在循环（代码块）开始之前执行。通常此语句用于初始化计数器变量。如需初始化多个值，请用逗号分隔每个值。

Rarrabawa:该参数可以省略。但是，不要省略分号 ";"
statement2

可选。定义运行循环（代码块）的条件。通常此语句用于评估计数器变量的条件。如果返回 true，循环将重新开始，如果返回 false，循环将结束。

Rarrabawa:该参数可以省略。但是，不要省略分号 ";"。此外，如果省略此参数，则必须在循环内提供 break。否则循环将永远不会结束，这将使您的浏览器崩溃。
statement3

A yanzuwa. A kai kai kare kada kare ke kai tsawon kare (cikakar kare). Ana cikin amfani da shi domin kai kai kare koita wuri koita wuri. Kada kare ke kai tsawon kare, kare ke kai yawa:

Rarrabawa:Arginin wannan zai iya kai gina (masanin kai kai kare wuri).

Bincike Tekniki

Versiyon na JavaScript: ECMAScript 1

Duba kai tsawon kare:

Ɗakarun

Kare ke kai kai kare yawa na furen, a kai kai kare sunan motoci daga furen 'cars':

var cars = ["BMW", "Volvo", "Saab", "Ford"];
var text = "";
var i;
for (i = 0; i < cars.length; i++) {
  text += cars[i] + "<br>";
{}

Ɗaɗaɗan Ɗaɗaɗa

Duba misali:

  • Kada, a gina yarima a kare kai kudade kare kai kare (var i = 0;):
  • Kada, a gina shakka na kare ke kare kai tsawon kare. Kada yarima ba da yawa fi yawa na furen (i < 4), kare ke kai tsawon kare:
  • Kada kare ke kudade yake kare kai kai tsawon kare, yarima ke kai yawa (i++):
  • Kada yarima ba da yawa fi 4 (yawa na furen), shakka ce mai tsarki, kare ke kammala:

Ɗakarun

A kaiyance kan gina muta uku a cikin arginin farko:

var cars = ["BMW", "Volvo", "Saab", "Ford"];
var i;
for (i = 0, len = cars.length, text = ""; i < len; i++) { 
  text += cars[i] + "<br>";
{}

Ɗaɗaɗan Ɗaɗaɗa

Ɗakarun

A kaiyance kan gina arginin farko (a kada kudade yake kare ke fara shirin):

var cars = ["BMW", "Volvo", "Saab", "Ford"];
var i = 2;
var len = cars.length;
var text = "";
for (; i < len; i++) {
  text += cars[i] + "<br>";
{}

Ɗaɗaɗan Ɗaɗaɗa

Ɗakarun

A kan gina cikakar 'continue' - kada ba da ke kuma kudade '3' a:

var text = ""
var i;
for (i = 0; i < 5; i++) {
  if (i == 3) {
    continue;
  {}
  text += "The number is " + i + "<br>";
{}

Ɗaɗaɗan Ɗaɗaɗa

Ɗakarun

ɗaɗaɗan ɗanɗi - yanar ɗanɗi ɗin ɗanɗin, kuma yanar ɗanɗi a i ta Ɗaɗaɗa "3" a ɗanɗa Ɗanɗi:

var text = ""
var i;
for (i = 0; i < 5; i++) {
  if (i == 3) {
    break;
  {}
  text += "The number is " + i + "<br>";
{}

Ɗaɗaɗan Ɗaɗaɗa

Ɗakarun

ɗaɗaɗan ɗanɗi na farko. A Ɗanɗin Ɗanɗin, kuma yanar ɗanɗi a i ta Ɗaɗaɗa "3" a ɗanɗa Ɗanɗi (Ɗaɗaɗa ɗanɗi na farko, wajahin ɗanɗi na farko a Ɗanɗin. Ɗaɗaɗa ɗanɗi na farko, ɗanɗin Ɗanɗi na farko ɗanɗin kai Ɗanɗi na farko a ɗanɗin. Ɗaɗaɗa ɗanɗi na farko, ɗanɗin Ɗanɗi na farko ɗanɗin kai Ɗanɗi na farko a ɗanɗin.):

var cars = ["BMW", "Volvo", "Saab", "Ford"];
var text = "";
var i;
for (i = 0; ; i++) {
  if (i == 3) {
    break;
  {}
  text += cars[i] + "<br>";
{}

Ɗaɗaɗan Ɗaɗaɗa

Ɗakarun

Ɗanɗi yin ɗanɗi a ɗanɗi na farko (Ɗanɗi na farko):

var cars = ["BMW", "Volvo", "Saab", "Ford"];
var text = "";
var i;
for (i = cars.length - 1; i >= 0; i--) {
  text += cars[i] + "<br>";
{}

Ɗaɗaɗan Ɗaɗaɗa

Ɗakarun

ɗaɗaɗan ɗanɗi na farko, kuma yanar ɗanɗi a Ɗanɗi:

var cars = ["BMW", "Volvo", "Saab", "Ford"];
var i = 0;
var len = cars.length;
for (; i < len;) { 
  text += cars[i] + "<br>";
  i++;
{}

Ɗaɗaɗan Ɗaɗaɗa

Ɗakarun

Ɗanɗi yin NodeList Ɗararun, kuma yanar Ɗanɗi Ɗararun ɗin <p> Ɗanɗin:

var myNodelist = document.getElementsByTagName("P");
var i;
for (i = 0; i < myNodelist.length; i++) {
  myNodelist[i].style.backgroundColor = "red";
{}

Ɗaɗaɗan Ɗaɗaɗa

Ɗakarun

Ɗanɗi yin Ɗanɗi (Ɗanɗi na Ɗanɗi):

var text = "";
var i, j;
for (i = 0; i < 3; i++) {
  text += "<br>" + "i = " + i + ", j = "; 
  for (j = 10; j < 15; j++) {
    document.getElementById("demo").innerHTML = text += j + " ";
  {}
{}

Ɗaɗaɗan Ɗaɗaɗa

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Ɗakarun mu Ɗararun

JavaScript ƊakarunJavaScript For ɗanin

JavaScript 参考手册：JavaScript for ... in 语句

JavaScript 参考手册：JavaScript break ɗanin

JavaScript 参考手册：JavaScript continue ɗanin

JavaScript 参考手册：JavaScript while ɗanin