Javascript trouble reversing loop

Question

This loop works 100% fine:

 for(m = 1; m < splitData.length; m++)

This one however throws errors! (Relating to loop body)

for(m = splitData.length; m > 1; m--)

The entire chunk of code is:

// Success
if (splitData[0] == "1") {
    // DbID, username, msg, date

 for(m = splitData.length; m > 1; m--){
        var splitMsg = splitData[m].split("¬");
        $('#<%=discussionBoard.ClientID %>').prepend('<div class="messageWrapper">
             <div class="messageHead">' + splitMsg[1] + '</div>
             <div class="messageTxt">' + splitMsg[2] + 
             '<div class="messageDetails">' + splitMsg[3] + 
             '</div></div></div>');
 }

The first index in splitData is just a 1 or 0 indicating if Ajax returned good data. I then want to loop through the rest of the input.

Mark Byers · Accepted Answer · 2011-02-11 17:45:13Z

4

You're off-by-one. Remember that the indexes in Javascript are 0-based, which means that they go from 0 to length - 1. Try this instead:

for (m = splitData.length - 1; m >= 1; m--)

answered Feb 11, 2011 at 17:45

Mark Byers

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4 Comments

Raynos Over a year ago

You dont want to check for >= to 0 just >

Mark Byers Over a year ago

@Raynos: I didn't notice that he wanted to ignore the first element. So, yes, I was off-by-one. :)

brent777 Over a year ago

To be the exact reverse of his original loop should it not be m > 0 not m >= 0?

dvhh Over a year ago

The most important part would be "m = splitData.length - 1"

brent777 · Accepted Answer · 2011-02-11 17:45:53Z

2

Have you tried

for(m = splitData.length - 1; m > 0; m--)

instead of:

for(m = splitData.length; m > 1; m--)

answered Feb 11, 2011 at 17:45

brent777

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Comments

Raynos · Accepted Answer · 2011-02-11 17:45:39Z

1

// count from 1 to splitData.length - 1

for(m = 1; m < splitData.length; m++)

// count from splitData.length to 2

for(m = splitData.length; m > 1; m--)

you want

for (m =splitData.length = 1; m > 0; m--)

answered Feb 11, 2011 at 17:45

Raynos

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