Default values of parametrs for own functions in jquery

Question

I am writing my own jQuery functions. Is it possible to set the default values of the function parameters?

score 9 · Answer 1 · answered Mar 14 '10 at 16:21

One way to do this is to check the parameters. For example:

function test(paramA) {
    if (paramA == null) {
        paramA = defaultValue;
    }
    // use paramA here
}

Another possibility is this:

function test() {
    var paramA = defaultValue;
    if (arguments.length == 1) {
        paramA = arguments[0];
    }
    // use paramA here
}

score 3 · Answer 2 · answered Jun 28 '11 at 08:36

3

i can't vote right now but agree with color2life.

a = a || "something"

is probably the most concise and readable version.

answered Jun 28 '11 at 08:36

Christian F

352
3
5

Don't forget the semicolon at the end of the line. Even though JS will put those in for you where it can, it's good practice to do it yourself. – DemitryT Aug 29 '12 at 19:55
This will fail with booleans. If you pass in false, and your default value is true, it will always be set to true. – KingOfHypocrites Sep 08 '13 at 18:44

score 2 · Answer 3 · answered Mar 14 '10 at 16:24

2

You might want to check for undefined instead of null.

var f=function(param){
  if(param===undefined){
    // set default value for param
  }
}

answered Mar 14 '10 at 16:24

Jeremy

22,188
4
68
81

score 0 · Answer 4 · answered Jun 14 '12 at 14:11

(function($) {
    $.fn.yourFunction= function(opts) {
        var options = $.extend({}, $.fn.yourFunction.defaults, opts);

        ....

        $.fn.yourFunction.defaults = {
        param1: "someval",
        param2: "",
        param3: "#ffffff"
    };

})(jQuery);

score 0 · Answer 5 · answered Feb 01 '11 at 14:57

0

if not defined then a have "something"

a = a || "something"; // setting default value

answered Feb 01 '11 at 14:57

Abdul Wahid

167
2
8

This will fail with booleans. If you pass in false, and your default value is true, it will always be set to true. – KingOfHypocrites Sep 08 '13 at 18:45

Default values of parametrs for own functions in jquery

5 Answers5