12.20---03if分支语句` ` ` `.....................................

var a = 1
if(a === 1){
  console.log(1)
}

if(a === 2){
  console.log(2)
}

var a = 100
if(a === 1){
  console.log(1)
}else if(a === 2){
  console.log(2)
}
else{
  console.log('a不等于1或者2')
}

var a = 100
if(a % 2 === 0){
  console.log('偶数')
}
else{
  console.log('不是偶数')
}

var a = 10
if(a >= 10){
  if(a <= 20){
    console.log('在')
  }
  else{
    console.log('不在')
  }
}
else{
  console.log('不在')
}

var a = 9
if(a >= 10 && a<=20){
  console.log('在')
}
else{
  console.log('不在')
}
var a = 4;
var num = 1 * (2 + 3) && a++ || 5 > 6 && 7 < 8 || !9
   console.log(num )
  var orign = 123.456789
  console.log(parseInt(orign*=100)/100)