Question

How to use substr() to get sub string of a string beginning at a specified location through a length in JavaScript

Answer 1

// str.substr(start[, length])

var s = "abcdefghijklmnop";

document.write(s.substr(0, 1) + "<br />");
document.write(s.substr(1, 1) + "<br />");
document.write(s.substr(0, 2) + "<br />");
document.write(s.substr(0, 3) + "<br />");
document.write(s.substr(1, 2) + "<br />");
document.write(s.substr(1, 3) + "<br />");
document.write(s.substr(10, 4) + "<br />"); // klmn
document.write(s.substr(30, 2) + "<br />");


/*
run:

a
b
ab
abc
bc
bcd
klmn

*/

 

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Answer 2

// str.substr(start[, length])

var s = "abcdefghijklmnop";

document.write(s.substr(-3, 1) + "<br />");
document.write(s.substr(-3, 2) + "<br />");
document.write(s.substr(-3, 3) + "<br />");
document.write(s.substr(-30, 2) + "<br />");
document.write(s.substr(-2) + "<br />");
document.write(s.substr(1) + "<br />");
document.write(s.substr(0) + "<br />");


/*
run:

n
no
nop
ab
op
bcdefghijklmnop
abcdefghijklmnop

*/

 

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