JavaScript function sending string but receiving Boolean value

Question

I am facing the unexpected behavior of javascript function. Im an passing the ID of a field as string to function but it is receiving as bool value. Please help the code is below.

Function

function page_smooth_scroll(target_id) {
    if (target_id =! null) {
        $j('html, body').animate({
            scrollTop: $j("#" + target_id).offset().top - 120
        }, 500);
    }
}

calling function

function validatePassword(){
            var validPassword = false;
            var pwd = $j("#Password").val().trim();
            var cfmPwd = $j("#ConfirmPassword").val().trim();
            if((pwd == "") || (cfmPwd == "")){
                $j("#ConfirmPassword").addClass("invalidPwd").nextAll("ul.err-msg").html("<li>Please enter Password</li>");
              //here id is passed as string
                page_smooth_scroll("ConfirmPassword");
                validPassword = false;
            }
            else{
                $j("#ConfirmPassword").removeClass("invalidPwd").nextAll("ul.err-msg").empty();
                if(pwd != cfmPwd){
                    $j("#ConfirmPassword").addClass("invalidPwd").nextAll("ul.err-msg").html("<li>Password does not match</li>");
                  //here id is passed as string
                    page_smooth_scroll("ConfirmPassword");
                    validPassword = false;
                }
                else{
                    $j("#ConfirmPassword").removeClass("invalidPwd").nextAll("ul.err-msg").empty();
                    validPassword = true;
                }
            }
            return validPassword;
        }

the image is below while debugging passing string

receiving bool

You are using a =! operator... Should be !=

Steve
– Steve

2016-10-25 06:20:45 +00:00
Commented Oct 25, 2016 at 6:20 — Steve
– Steve, Commented Oct 25, 2016 at 6:20

Erik · Accepted Answer · 2016-10-25 06:21:18Z

5

if (target_id =! null) {

I think you mean a != b

Because a=!b means a = !b which means "assign the opposite boolean value", which will indeed turn anything into a boolean.

Next time if you think a function is "receiving a boolean", make sure to debug the value before running any statements. I'm sure it's still a string when going into the function.

answered Oct 25, 2016 at 6:21

Erik

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1 Comment

Thilo Over a year ago

if (target_id != null) can in most cases (when your ids cannot be empty strings, or 0, or false) also be written as if (target_id).

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