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Tibor Ruzinyi
17,968 PointsFor loops with arrays question : += vs. +
Hello,
Is there a specific reason to use in Daves code :
listHtml += '</ol>';
instead:
listHtml + '</ol>';
2 Answers
Sean T. Unwin
28,690 Points+= is a shortcut to say 'this equals this plus whatever comes next'.
In terms of Strings, it will concatenate (or attach to) the existing String with the String that is presented after the +=.
When dealing with Numbers, this will add the Number following += to the existing Number. It is also possible to use -= on Numbers as well where this will subtract the Number after -= from the Number before the -=.
/* STRINGS */
listHtml += '</ol>';
/* is the same as */
listHtml = listHtml + '</ol>';
/* is the same as */
listHtml.concat('</ol>');
/* NUMBERS */
var a = 3;
var b = 7;
/* += */
a += b; // 'a' is now 10;
/* is the same as */
a = a + b;
/* -= */
b -= a; // 'b' is now 4 (using original variable values)
/* is the same as */
b = b - a;
Tibor Ruzinyi
17,968 PointsThank you very much for your answer, But why just not use listHtml + something. If i use this i will get the same output.
Sean T. Unwin
28,690 PointsIt saves having to type listHtml out twice, i.e. listHtml = listHtml + something;.
Stephen Little
8,312 PointsStephen Little
8,312 PointsDon't know much about JavaScript but isn't the first one assigning the value of listHtml the value of listHtml + the order list ending.
So this
listHtml +='</ol>';would give you what ever value was in the listHtml var and add the order list end tag to the end of it.
Just what I saw at first glance... cheers! Stpehen