There are two approaches:
Method 1 (!==not equal) //recommend
var str_1 ="test 1";
var str_2 = "test 2";
if (str_1 != str_2 ){ //true
alert("str_1 != str_2");
}else{
alert("str_1 == str_2");
}
Method 2 (!== not equal value or not equal type)
if (str_1 !==str_2 ){ //true
//do something
}else{
//do something
}
