Does Vbscript's Isempty Have An Equivalent In Javascript?

August 21, 2024 Post a Comment

Using Javascript, is there an equivalent function or functionality so VBScript's IsEmpty function? The VBScript function returns whether the given variable is 'empty', e.g. since

Solution 1:

JavaScript has a number of different values which could be considered "empty" and a number of different ways to test for empty.

First things that are empty:

undefined: values that have been not been assigned. if you create a variable but don't assign anything to it, this is what it will contain.
null: this is an object value that can be assigned to any var.

Next how to test for them. JavaScript is loosely typed with a lot of implicit type conversion. This means that when two values are of different types, the standard equals operator == performs type coersion. The triple-equals operator does not perform type coersion which makes it the best operator for testing against very specific values.

you can test the type of a value which returns a string that can be tested (note the triple-equals operator):
```
if ("undefined" === typeof myFoo) { /* this would be considered empty */ }
```

you can test against the keyword undefined (note the triple-equals operator):

if (undefined === myFoo) { /* this would be considered empty */ }

you can test against the keyword null (note the triple-equals operator):

if (null === myFoo) { /* this would be considered empty */ }

you can test against the empty string "" (note the triple-equals operator):
```
if ("" === myFoo) { /* this would be the empty string */ }
```

if you are expecting a value which would not normally be coerced to the boolean value false, then you can test for its existence by just testing it directly within the if statement:

if (!myFoo) {
    /* this would be any falsy value, including false, null, 0, undefined */
} else {
    /* this would be any truthy value, including objects,
    numbers other than zero, Dates, etc. */
}

Most of the time, if you're expecting something "truthy", you can just test it directly and it will be coerced to a boolean value. So in short, you could probably get away with defining it as this:

functionisEmpty(value) {
    return !value;
}

But it often makes more sense just to put a ! or !! before the object to get its value. Just be careful if you are expecting false or 0 (zero) as valid values. In those cases it is better to test the typeof the object and make choices accordingly.

Solution 2:

Not sure, if this is what it should be

typeof variable == "undefined"

Solution 3:

functionIsEmpty( theValue ) 
{ 
    if ( theValue === undefined ) 
    { 
        returntrue; 
    } 
    returnfalse; 
}

Solution 4:

function isEmpty(value){ return value == null || value === ""; }

Solution 5:

Not there isnt.

You will have always to test your variables against "null", undefined and "". (that is boring)

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