Question

I need to learn how to pass an associative array to a function so that I could do the following within the function:

function someName($argums) {
    if (gettype($argums) != 'array' || 
       !array_key_exists('myOneKey', $argums) ||
       !array_key_exists('myOtherKey', $argums)) {              
           return false;
    } 

    /*do other stuff*/
}

(That’s how I would do it in PHP that I am looking for in JavaScript.)

Answer 1

All Javascript objects are associative arrays, so this is really easy. You actually have a few options, because an object can have properties of its own, properties it inherits from its prototype object, properties with undefined values, and properties with “falsey” values (undefined, null, 0, "", or of course, false). (There’s a difference between an object not having a property and having one with an undefined value.)

Checking to see if the object has the properties itself: You use obj.hasOwnProperty:

function someName(obj) {
    if (!obj ||
        !obj.hasOwnProperty('myOneKey') ||
        !obj.hasOwnProperty('myOtherKey'))
        return false;
    }
    // Do other stuff
}

Checking to see if the object has the property itself or via its prototype: You use propName in obj:

function someName(obj) {
    if (!obj ||
        !('myOneKey' in obj) ||
        !('myOtherKey' in obj))
        return false;
    }
    // Do other stuff
}

Checking to see if the object has the property (directly, or via prototype) and it’s not undefined: You look for an undefined value:

function someName(obj) {
    if (!obj ||
        typeof obj.myOneKey === "undefined" ||
        typeof obj.myOtherKey === "undefined")
        return false;
    }
    // Do other stuff
}

Checking to see if the property is falsey (undefined, null, 0, "", or of course, false), regardless of why: Just use !:

function someName(obj) {
    if (!obj ||
        !obj.myOneKey ||
        !obj.myOtherKey)
        return false;
    }
    // Do other stuff
}

Regardless, usage:

var obj = {
    myOneKey: 'fred',
    myOtherKey: 'barney'
};
someName(obj);