[removed] indexOf vs. Match when Searching Strings?

Question

Readability aside, are there any discernable differences (performance perhaps) between using

str.indexOf("src") 

and

Answer 1

The return values are different

Aside from the performance implications, which are addressed by other answers, it is important to note that the return values for each method are different; so the methods cannot merely be substituted without also changing your logic.

Return value of .indexOf: integer

The index within the calling String object of the first occurrence of the specified value, starting the search at fromIndex.
Returns -1 if the value is not found.

Return value of .match: array

An Array containing the entire match result and any parentheses-captured matched results.
Returns null if there were no matches.

Because .indexOf returns 0 if the calling string begins with the specified value, a simple truthy test will fail.

For example:

Given this class…

class='DisablesGuiClass-2345-2d73-83hf-8293 redBorder' 

…the return values for each would differ:

//  returns `0`, evaluates to `false`
if (string.indexOf('DisablesGuiClass-')) {
    … // this block is skipped.
}

vs.

//  returns `["DisablesGuiClass-"]`, evaluates to `true`
if (string.match(/DisablesGuiClass-/)) { 
    … // this block is run.
}

The correct way to run a truthy test with the return from .indexOf is to test against -1:

if (string.indexOf('DisablesGuiClass-') !== -1) {
//  ^returns `0`                        ^evaluates to `true`
    … // this block is run.
}