Javascript function fails to return element

问题

So I'm working with the Handsontable jQuery plugin for a project at the moment, and I've written some custom functions to work with it.

The function I'm currently having trouble with is one I've written to return the currently selected cell(when the user has only selected one, not multiple, and yes that is checked for).

Here is my code:

function getCurrentCell(){
    var selection = $('div.current');
    var left = selection.offset().left;
    var right = left + selection.width();
    var top = selection.offset().top;
    var bottom = top + selection.height();
    $('div.active').find('table').find('td').each(function(){
        if($(this).offset().left >= left && $(this).offset().left <= right && $(this).offset().top >= top && $(this).offset().top <= bottom){
            return this;
        }
    });
    return false;
}

However, whenever I call the function such as:

var cell = getCurrentCell();

And then attempt to alert(cell) or console.log(cell), I get a false return value.

My initial thought would be that somehow the coordinates would be off, and therefore no element would be found matching the criteria, so I attempted to check by adding...

$(this).css('background-color', 'black');

...right before the return this line. That way, if the right table cell is found, it will show up on screen before actually returning in code. Funny thing is, the correct cell always has its background color changed properly. So, this function is finding the correct cell, and it is executing the code within the if loop, but when I try and capture the return value into a variable, that variable is always false.

Any help would be great! Thanks SO!

回答1:

You are using .each() with a function

.each(function(){
    ...
    return this;
});
return false;

This will return from the callback (and maybe stop the each-loop if this was false), but never break out and return from the outer getCurrentCell function! So, that one will always return false.

Quick fix:

var result = false;
<...>.each(function(){
    if (<condition>) {
        result = <found element>;
        return false; // break each-loop
    }
});
return result; // still false if nothing found

回答2:

Currently there is a better way to get currently selected in Handsontable. Just use the following methods from Handsontable:

handsontable('getSelected') - Returns index of the currently selected cells as an array [topLeftRow, topLeftCol, bottomRightRow, bottomRightCol]

handsontable('getCell', row, col) - Return element for given row,col

All methods are described here: https://github.com/warpech/jquery-handsontable

来源：https://stackoverflow.com/questions/11569516/javascript-function-fails-to-return-element

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