How to use if statement in js

Answer 1

if (condition) {
//Statements go here
}

Answer 2

If statements in JS are conditional statements just like in other languages. What dont you understand specifically?
e.g.
if(condition){ // if something is true, e.g if x===1, then...
//execute this block of code
}
//if x === 1 is not true, ignore the above block of code and...
// run this other code...

Like that.Hope its clear

Answer 3

if (condition) {
statements
}

Example:

var x==1;
if (x==1) {
document.write("x is equal to 1");
}

Answer 4

if (something happens) {
Do something
}