slice(), subString(), substr()

String.prototype.slice () is a method of slicing tool js string of a string for 'clipping' operation, without changing the original string.

'helloworld'.slice (0,5); // ' Hello '; 
' helloworld'.slice (. 5); // 'World'; default to the end
 'helloworld'.slice (-5); // ' World '; 10-5 = 5; // first parameter is greater than the second argument is returned null character. 
' helloworld'.slice (5,1); // '' 
'helloworld'.slice (-1, - 5); // ''

substring () and slice () is a part can be cut out from the original string inside, but substring () little features.

1. The first parameter is greater than the second parameter, both automatically exchange position;

2. Negative automatically converted to 0;

Two or more of the following effects will be obtained:

'JavaScript'.substring(4, -3); // 'Java'

The principle is: (. 4, 0) => (0,. 4) => 'the Java'

 

Note that, if the same two parameter, the empty string;

'javascript'.slice(2,2); // ''
'javascript'.subsring(2,2); // ''

 

String.prototype.substr () between String.prototype.slice () and String.prototype.substring () between the negative index which will be converted to 0, when the first parameter is not large than the second exchange position.