JavaScript程序中的流程控制语句用法总结

if (condition) statement1 else statement2

if (condition1) statement1 else if(condition2) statement2 else statement3

switch(expression) {
  case value: statement
    break;
  case value: statement
    break;
  case value: statement
    break;
  default: statement
}

var num = 25;
switch (true) {
  case num < 0:
    alert("Less than 0");
    break;
  case num >= 0 && num <= 10:
    alert("Between 0 and 10");
    break;
  case num > 10 && num <= 20:
    alert("Between 10 and 20");
    break;
  default:
    alert("More than 20");
}

do {
  statement
} while (expression);

var i = 0;
  do {
    i += 2;
  } while (i < 10);
  alert(i);//10

while(expression) statement

 var i = 0;
  while(i < 10) {
    i += 2;
  }
  alert(i);//10

for(var i = 0;i < 10;i++) {
  alert(i);
}

for (var prop in window) {
    console.log(prop);
  }

 var num = 0;
  for(var i = 1;i < 10;i++) {
    if(i % 5 == 0) {
      break;
    }
    num++;
  }
  alert(num);//4

var num = 0;
    for(var i = 1;i < 10;i++) {
      if(i % 5 == 0) {
        continue;
      }
      num++;
    }
    alert(num);//8