how parameter inside function works?

Question

html

<p>This is a <b>bold</b> paragraph.</p>
<button>Add</button>

jquery

$("button").click(function(){
    $("p").text(function(i,origText){
      return "Old text: " + origText + " New text: Hello world! (index: " + i + ")"; 
    });
  });

I would like to know origText is not called outside function but it is returning the value. How?

demo

score 2 · Answer 1 · edited May 23 '17 at 12:05

2

As docs says

function(index, text)

A function returning the text content to set. Receives the index position of the element in the set and the old text value as arguments.

And How does jQuery’s .text() work, internally?

edited May 23 '17 at 12:05

Community

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answered Jul 17 '13 at 12:01

Suresh Atta

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score 2 · Answer 2 · answered Jul 17 '13 at 12:01

2

The actual method text takes a function as a parameter. The function passed to text may contain two parameters, the first of which receives the index, the second the original text.

answered Jul 17 '13 at 12:01

Plymouth223

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text() function must contain two parameteres? – Bhojendra Rauniyar Jul 17 '13 at 12:03
The function *passed* to the text method may contain two parameters, in your case i and origText. – Plymouth223 Jul 17 '13 at 12:05
@C-Link No.Not necessarily.See the others methods in docs.You can use it with various no.of params. – Suresh Atta Jul 17 '13 at 12:06

score 0 · Answer 3 · answered Jul 17 '13 at 12:03

Function text does some preparations about input nodes and then runs callback provided by user (your function), and it pass to your callback this two arguments (which prepared on "some preparations") step. If you want exact code, you can read jQuery source.

score 0 · Answer 4 · answered Jul 17 '13 at 12:07

0

In simple:

text(function(whatever){
      return whatever; // returns the text what is the text it has.
    });

In your example p has text : This is a bold paragraph.

return whatever will return your text : This is a bold paragraph.

answered Jul 17 '13 at 12:07

Navin Rauniyar

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how parameter inside function works?

4 Answers4