How do I pass variables into a JavaScript function?

Question

Is it possible to pass variables into a js function? See code:

function checkStartPrice (){
    if ($('#StartingPrice')[0].value.length == 0){
        alert("The 'Starting Price' cannot be left empty!");
        return false;
     } else {
        var BuyItNowPrice = parseFloat($('#BuyItNowPrice').val());
        var StartingPrice = parseFloat($('#StartingPrice').val());
        var Reserve = parseFloat($('#Reserve').val());
        if((BuyItNowPrice <= StartingPrice) && (StartingPrice > 0)){
            alert("The 'Buy It Now' price must be higher...");
            return false;
        }
        if((Reserve <= StartingPrice) && (StartingPrice > 0)){
            alert("Your 'Reserve Price' must be higher...");
            return false;
        }
        return true;
    }
}

I'd like to take the var BuyItNowPrice = parseFloat($('#BuyItNowPrice').val()); etc and place them outside the function, then call them in.

The reason is I have 3 of these functions so these 3 variables (BuyItNowPrice, StartingPrice, Reserve) are repeated 9 times, 3 in each function.

Is there a way of doing this?

Any help would be Greatly Appreciated, Thanks

Why don't you move the variables into the global scope?

Reporter
– Reporter

2011-04-27 09:04:50 +00:00
Commented Apr 27, 2011 at 9:04 — Reporter
– Reporter, Commented Apr 27, 2011 at 9:04

James · Accepted Answer · 2011-04-27 09:38:05Z

2

A simple example of passing variables into a function is below. When you declare a function, you can also declare some arguments for the function by putting them inside the function() brackets. You can use whatever letter/name you like to represent the arguments - when you CALL the function, you pass through the variables.

// put arguments into the function declaration - a,b,c
function myfunction(a, b, c) {

// use these arguments within the function
return (a+b+c);
}

// declare the variables outside the function
var first_variable = 1;
var second_variable = 2;
var third_variable = 3;

// returns '6'
myfunction(first_variable, second_variable, third_variable);

answered Apr 27, 2011 at 9:38

James

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Comments

Ammu · Accepted Answer · 2011-04-27 09:05:04Z

1

You can make these variables global by taking it out of the fn

    BuyItNowPrice = parseFloat($('#BuyItNowPrice').val());
    StartingPrice = parseFloat($('#StartingPrice').val());
    Reserve = parseFloat($('#Reserve').val());
    fn1(){}     
    fn2(){}
    fn3(){}

Now you can use these variables in all the three functions.

answered Apr 27, 2011 at 9:05

Ammu

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1 Comment

Nasir Over a year ago

How do I pass the variables into the function? Sorry I'm a beginner a JavaScript, Thanks

Anji · Accepted Answer · 2011-04-27 09:16:18Z

1

Make those three variables global. To make them global you just need to have those variables outside any function. In javascript if any variable which doesnot appear in any functions, then its scope is global.

To answer your first question, Yes it is possible to pass variables to functions in javascript. you can just send the variables as arguments to the function.

sample: function myfucn(a, b) { //you implementation here.}

edited Apr 27, 2011 at 9:16

answered Apr 27, 2011 at 9:09

Anji

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3 Comments

ThiefMaster Over a year ago

I think your explanation is not very good. Actually, a variable that was never locked to a scope using var is global. Also a variable defined using var in the global scope is global. To allow everyone to see that your variable is global you should use var yourVar; in the global scope (i.e. outside a function).

Anji Over a year ago

@ThiefMaster my intention was same.. may be my English was bad :D

Nasir Over a year ago

@ThiefMaster - I have placed the variables as global outside the function...but the variables are NOT hitting the else{} ...? I'm confused

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