What is the difference between String.slice and String.substring?

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 return the empty string. ("")
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()

substr: It's providing us to fetch part of the string based on specified index. syntax of substr- string.substr(start,end) start - start index tells where the fetching start. end - end index tells upto where string fetches. It's optional.

slice: It's providing to fetch part of the string based on the specified index. It's allows us to specify positive and index. syntax of slice - string.slice(start,end) start - start index tells where the fetching start.It's end - end index tells upto where string fetches. It's optional. In 'splice' both start and end index helps to take positive and negative index.

sample code for 'slice' in string

var str="Javascript";
console.log(str.slice(-5,-1));

output: crip

sample code for 'substring' in string

var str="Javascript";
console.log(str.substring(1,5));

output: avas

[*Note: negative indexing starts at the end of the string.]