How do I test a variable passed into a function?

Question

Quick question, I'm trying to pass a value to a variable and then run a function if the variable was set to something specific. How do I do that?

I have the following example where I want to assign the value name to a form field if the variable type is set to 1.

function test(name,type) {
  if (type=1) {
    document.myform.name.value = name;
  }
}

and a link in the body of the html:

<a href="javascript:test('myname','1');">FILL IN MY NAME</a>

I also tried the following with no luck:

function test(name,type) {
  var checktype = type;
  if (checktype = 1) {
    document.myform.name.value = name;
  }
}

I'm pretty sure something like this is possible, just not sure what I'm doing wrong.

Answer 1

Try this:

function test(name,type) {
  var checktype = type;
  if (checktype == 1) {
    document.myform.name.value = name;
  }
}

You were missing ==

Answer 2

You want to use ==, not =. Using a single symbol will assign the value of 1 to the variable checktype, rather than testing for equality:

function test(name,type) {
  if (type == 1) {
    document.myform.name.value = name;
  }
}

Answer 3

Javascript uses == for equality checks.

Answer 4

function test(name,type) {
  if (type === "1") {
    document.myform.name.value = name;
  }
}

No need to use an additional variable inside the function for storing the value. Also use ===' instead of==` if you know the type of the variable.

See Strict equal

Returns true if the operands are strictly equal (see above) with no type conversion.

Answer 5

function test(name,type) {
  if (type==1) {
    document.myform.name.value = name;
  }
}

Answer 6

You need to use a comparison operator instead of an assignment operator:

function test(name, type) {
  if (type == 1) {
    document.myform.name.value = name;
  }
}

If you’re using an assignment operator, the whole expression evaluates to the assigned value. That means type = 1 evaluates to 1 that is equal true and the branching condition is always fulfilled.

Answer 7

To avoid this type errors try to do this..

function test(name,type) {
  if (1 == type) {
    document.myform.name.value = name;
  }
}

In this case, if you type by mistake, 1=type, then you get an error and you locate it right way.