Javascript syntax issue?

Question

Is the IF conditional logic correct? It works for test1 but not test2 or ""

      if($(this).attr("value") === ("test1" || "test2" || ""))
      {
          submitForm($(this).attr("value"));
      }

If it doesn't do what you want, then the logic isn't correct. — user2736012, Sep 10 '13 at 22:27
possible duplicate of [Javascript: The prettiest way to compare one value against multiple values](http://stackoverflow.com/questions/9121395/javascript-the-prettiest-way-to-compare-one-value-against-multiple-values) or [A jQuery 'if' condition to check multiple values](http://stackoverflow.com/questions/10597015/a-jquery-if-condition-to-check-multiple-values) or [Combining multiple conditions into one in Javascript](http://stackoverflow.com/questions/1561257/combining-multiple-conditions-into-one-in-javascript) — Bergi, Sep 10 '13 at 22:29

Jason McCreary · Accepted Answer · 2013-09-10T22:33:35.927

3

You need to test again each possible value:

if($(this).attr("value") === "test1" || $(this).attr("value") === "test2" || $(this).attr("value") === ""))

Cleaned with a temp variable:

var attribute = $(this).attr("value");
if(attribute === "test1" || attribute === "test2" || attribute === ""))

Alternative, you could use indexOf() as shorthand:

if (["test1", "test2", ""].indexOf($(this).attr("value")) != -1)

edited Sep 10 '13 at 22:33

answered Sep 10 '13 at 22:27

Jason McCreary

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No shortcut for this? – Yetimwork Beyene Sep 10 '13 at 22:28
3

Use a variable for goodness sake. – user2736012 Sep 10 '13 at 22:29
@user2736012, of course. I was trying to relay the repetition. – Jason McCreary Sep 10 '13 at 22:30
1

@YetimworkBeyene - Yes, there is a shortcut: write a function or use one of the _multiple_ alternatives suggested by the links in Bergi's comment. – jahroy Sep 10 '13 at 22:34
I have yet to figure out if someone (@user2736012) is annoyed with the question, why waste their time responding. – Yetimwork Beyene Sep 10 '13 at 22:36
@YetimworkBeyene - I don't see anything wrong with user2736012's suggestion to make things cleaner by using a variable. Not sure why you think it shows annoyance. – jahroy Sep 10 '13 at 22:39
1

Everyone can relax, the question was closed as a duplicate. – Jason McCreary Sep 10 '13 at 22:40
@jahroy what does goodness sake means? Happy? Don't assume i didn't do any research – Yetimwork Beyene Sep 10 '13 at 22:43
"_Goodness sake_" doesn't mean annoyance. It just says "_please_" with emphasis. I don't need to assume you didn't do any research, your question speaks for itself. – jahroy Sep 10 '13 at 22:44

Niccolò Campolungo · Answer 2 · 2013-09-10T22:36:30.640

if($(this).attr("value") === ("test1" || "test2" || "")) {
    submitForm($(this).attr("value"));
}

What is going on here? The OR || operator returns the first truthy value, so the returned value of ("test1" || "test2" || "") is "test1". In this case this expression is interpreted in this way:

(("test1" || "test2") || "")

The first expression evaluated is "test1" || "test2", which returns "test1" since it is a truthy value. The second expression is "test1" || "". Again it returns "test1"(moreover "" is falsy).

A very fast way to write something similar to this is to search inside an array:

var acceptedValues = ["test1", "test2", ""];
if(acceptedValues.indexOf(this.value) != -1) submitForm(this.value);

In this simple operations jQuery is not needed!

For supporting older browser, you should use $.inArray() – A. Wolff Sep 10 '13 at 22:32 — A. Wolff, Sep 10 '13 at 22:32

score 0 · Answer 3 · answered Sep 10 '13 at 22:28

0

if($.inArray(this.value,['test1','test2','test3']) != -1){
    //...
}

answered Sep 10 '13 at 22:28

A. Wolff

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Javascript syntax issue?

3 Answers3