if(boolean_expression) {
   // statement(s) will execute if the boolean expression is true  
}

var  num:number = 5
if (num > 0) { 
   console.log("number is positive") 
}

//Generated by typescript 1.8.10
var num = 5;
if (num > 0) {
   console.log("number is positive");
}

number is positive