What is the difference between String.slice and St

Question

Does anyone know what the difference is between these two methods:

String.protorype.slice
String.protorype.substring

Answer 1

For slice(start, stop), if stop is negative, stop will be set to: string.length – Math.abs(stop), rather (string.length – 1) – Math.abs(stop).

Answer 2

The only difference between slice and substring method is of arguments

Both take two arguments e.g. start/from and end/to.

You cannot pass a negative value as first argument for substring method but for slice method to traverse it from end.

Slice method argument details:

REF: http://www.thesstech.com/javascript/string_slice_method

Arguments

start_index Index from where slice should begin. If value is provided in negative it means start from last. e.g. -1 for last character. end_index Index after end of slice. If not provided slice will be taken from start_index to end of string. In case of negative value index will be measured from end of string.

Substring method argument details:

REF: http://www.thesstech.com/javascript/string_substring_method

Arguments

from It should be a non negative integer to specify index from where sub-string should start. to An optional non negative integer to provide index before which sub-string should be finished.

Answer 3

slice() works like substring() with a few different behaviors.

Syntax: string.slice(start, stop);
Syntax: string.substring(start, stop);

What they have in common:

1. If start equals stop: returns an empty string
2. If stop is omitted: extracts characters to the end of the string
3. If either argument is greater than the string's length, the string's length will be used instead.

Distinctions of substring():

1. If start > stop, then substring will swap those 2 arguments.
2. If either argument is negative or is NaN, it is treated as if it were 0.

Distinctions of slice():

1. If start > stop, slice() will NOT swap the 2 arguments.
2. If start is negative: sets char from the end of string, exactly like substr() in Firefox. This behavior is observed in both Firefox and IE.
3. If stop is negative: sets stop to: string.length – Math.abs(stop) (original value), except bounded at 0 (thus, Math.max(0, string.length + stop)) as covered in the ECMA specification.

Source: Rudimentary Art of Programming & Development: Javascript: substr() v.s. substring()

Answer 4

The one answer is fine but requires a little reading into. Especially with the new terminology "stop".

My Go -- organized by differences to make it useful in addition to the first answer by Daniel above:

1) negative indexes. Substring requires positive indexes and will set a negative index to 0. Slice's negative index means the position from the end of the string.

"1234".substring(-2, -1) == "1234".substring(0,0) == ""
"1234".slice(-2, -1) == "1234".slice(2, 3) == "3"

2) Swapping of indexes. Substring will reorder the indexes to make the first index less than or equal to the second index.

"1234".substring(3,2) == "1234".substring(2,3) == "3"
"1234".slice(3,2) == ""

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General comment -- I find it weird that the second index is the position after the last character of the slice or substring. I would expect "1234".slice(2,2) to return "3". This makes Andy's confusion above justified -- I would expect "1234".slice(2, -1) to return "34". Yes, this means I'm new to Javascript. This means also this behavior:

"1234".slice(-2, -2) == "", "1234".slice(-2, -1) == "3", "1234".slice(-2, -0) == "" <-- you have to use length or omit the argument to get the 4.
"1234".slice(3, -2) == "", "1234".slice(3, -1) == "", "1234".slice(3, -0) == "" <-- same issue, but seems weirder.

My 2c.

Answer 5

The difference between substring and slice - is how they work with negative and overlooking lines abroad arguments:

substring (start, end)

Negative arguments are interpreted as zero. Too large values ​​are truncated to the length of the string:   alert ( "testme" .substring (-2)); // "testme", -2 becomes 0

Furthermore, if start > end, the arguments are interchanged, i.e. plot line returns between the start and end:

alert ( "testme" .substring (4, -1)); // "test"
// -1 Becomes 0 -> got substring (4, 0)
// 4> 0, so that the arguments are swapped -> substring (0, 4) = "test"

slice

Negative values ​​are measured from the end of the line:

alert ( "testme" .slice (-2)); // "me", from the end position 2
alert ( "testme" .slice (1, -1)); // "estm", from the first position to the one at the end.

It is much more convenient than the strange logic substring.

A negative value of the first parameter to substr supported in all browsers except IE8-.

If the choice of one of these three methods, for use in most situations - it will be slice: negative arguments and it maintains and operates most obvious.

Answer 6

Ben Nadel has written a good article about this, he points out the difference in the parameters to these functions:

String.slice( begin [, end ] )
String.substring( from [, to ] )
String.substr( start [, length ] )

He also points out that if the parameters to slice are negative, they reference the string from the end. Substring and substr doesn´t.

Here is his article about this http://www.bennadel.com/blog/2159-using-slice-substring-and-substr-in-javascript.htm