Added 'splice' function to the string object

[AmatanHead]

A splice function for strings could be useful. It takes string and inserts another string before the specified position.

[arian]

Your pull request looks really good!

Also there is no doubt this function can be useful. The question is whether this should be in -core, or somewhere else.

Let's hear what others have to say...

[ibolmo]

This doesn't seem intuitive. One could argue this would have been the result: 'Add substring'

[ibolmo]

I know it's suppose to mimic Array.splice ... just not exactly very readable.

[ibolmo]

If this is useful for anyone else, then we can go ahead and pull into Core. I'm arguing the readability, but it's a moot argument if others pick up the idea.

[ibolmo]

Also, this is missing specs. I would assume that the specs would need to conform to Array.splice's specs (or at least generally). totally skipped the last file. gj!

[ibolmo]

Missing space after 0, pos

[arian]

If it should work the same as Array#splice, you should be able to insert all rest arguments in between.

[megawac]

Shouldn't ins be optional

[arian]

String#splice should obviously work the same as Array#splice. Too bad Array.prototype.splice.call('abc', 1, 0) doesn't work on strings in JS.

[arian]

One difference, looking at Array#splice, is that it returns an array of the removed items.
I think for here this should be very unintuitive, and not really possible.

[AmatanHead]

I see two ways to fix this: first is to try to fully mimic array.splice, second is to brake intuitive similarity and invite something new.

[ibolmo]

What if remove was < 0?
What if remove and insert was missing?
What if position, remove, and insert were missing?

[ibolmo]

What if remove was > this.length?

[ibolmo]

What if position was > this.length? Pad with empty string?

[megawac]

You can also just delegate to splice?

var t = this.split("");
t.splice(pos, rem, ins);
return t.join("");

[ibolmo]

Re: the stick to Array.splice mimicry vs. venture into splice-like

I would start with the Specs, and define the questions and answers. I'd personally prefer to write something like:

'Some string'.splice('my other string', 5);    // 'Some my other string'
'abc'.splice(' ', 1);                          // 'a c'
'abc'.splice(' ', 1, 2);                       // 'a  c'

myString.splice(withAnother, optStartPosition, optLength);

'abc'.splice('def');                          // 'abcdef'

[arian]

@ibolmo what if you just want to remove a part of the string, and don't want to insert something new, then rather than passing an empty string/value (null/undefined), the replacement string should be the last argument, like it is in Array.splice... Then it's really optional.

[AmatanHead]

If so, I would prefer to split this operation into paste(what, optPosition), insert(what, optPosition) and delete(length, optPosition).

'abc'.paste('q') // 'qabc'
'abc'.paste('q', 1) // 'aqbc'
'abc'.insert('q') // qbc
'abc'.insert('q', 1) // aqc
'abc'.remove(1) // 'bc'
'abc'.remove(1, 1) // 'ac'

[bad idea]

[AmatanHead]

... or, as suggests @megawac, just delegate it. May even better:

splice: function() {
    var t = this.split("");
    console.log(t.splice.apply(t, arguments));
    return t.join("");
}

or return two arguments:

splice: function() {
    var t = this.split(""),
        change = t.splice.apply(t, arguments).join(""),
        out = t.join("");
    return [out, change];
}

"12345".splice(1, 2, 'Q', 'W', 'ERTY') // ["1QWERTY45", "23"]

[AmatanHead]

So here's a new implementation. Now it's really close to array.splice because it's based on array.splice.

• The syntax is very similar to array.splice
• Negative positions are explicitly controlled.
• It's available to get removed string.

[AmatanHead]

Is something wrong to this PR? Why so silent here?

[SergioCrisostomo]

@AmatanHead really nice PR!

@ibolmo, @arian anything you would like to comment, discuss or add here?

[nfroidure]

splice is a modificative function for arrays. having splice on strings would assume it either is. But strings cannot be modified in JavaScript, you still get a new string.

If you really need this method, IMO, it should be slice, not splice.

[olvlvl]

I share the opinion of @nfroidure. Consider the following code:

String.implement({

    splice: function() {

        arguments[0] += (arguments[0] < 0 ? this.length + 1 : 0);
        var return_both = (typeof arguments[arguments.length - 1] === 'boolean' ? arguments[--arguments.length] : false),
        t = this.split(""),
        change = t.splice.apply(t, arguments).join(""),
        out = t.join("");
        return (return_both ? [out, change] : out);
    }

})

var str = "Madonna"
, arr = [ 1, 2, 3, 4 ]

str.splice(2, 1)
arr.splice(2, 1)

console.log(str)
console.log(arr)

str is still "Madonna" when it should be "Maonna", but arr is [ 1, 2, 4 ] as expected.

The function should be renamed as slice, although that function already exists:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/slice