未捕获的类型错误：无法设置未定义的属性“左”

Question

Uncaught TypeError: Cannot set property 'left' of undefined. at index.html:723 at dispatch (jquery.js:3) at r.handle (jquery.js:3) What should i do with this help me..

<script type="text/javascript">
jQuery(window).scroll(function(){
if(jQuery(window).scrollTop()<50){
jQuery('#rocketmeluncur').slideUp(500);
}else{
jQuery('#rocketmeluncur').slideDown(500);
}
var ftrocketmeluncur = jQuery("#ft")[0] ? jQuery("#ft")[0] : jQuery(document.body)[0];
var scrolltoprocketmeluncur = $('rocketmeluncur');
var viewPortHeightrocketmeluncur = parseInt(document.documentElement.clientHeight);
var scrollHeightrocketmeluncur = parseInt(document.body.getBoundingClientRect().top);
var basewrocketmeluncur = parseInt(ftrocketmeluncur.clientWidth);
var swrocketmeluncur = scrolltoprocketmeluncur.clientWidth;
if (basewrocketmeluncur < 1000) {
var leftrocketmeluncur = parseInt(fetchOffset(ftrocketmeluncur)['left']);
leftrocketmeluncur = leftrocketmeluncur < swrocketmeluncur ? leftrocketmeluncur * 2 - swrocketmeluncur : leftrocketmeluncur;
scrolltoprocketmeluncur.style.left = ( basewrocketmeluncur + leftrocketmeluncur ) + 'px';
} else {
scrolltoprocketmeluncur.style.left = 'auto';
scrolltoprocketmeluncur.style.right = '10px';
}
})

jQuery('#rocketmeluncur').click(function(){
jQuery("html, body").animate({ scrollTop: '0px',display:'none'},{
duration: 600,  
easing: 'linear'
});

var self = this;
this.className += ' '+"launchrocket";
setTimeout(function(){
self.className = 'showrocket';
},800)
});
</script>

Answer 1

jQuery(window).scroll(function() {
    if (jQuery(window).scrollTop() < 50) {
        jQuery('#rocketmeluncur').slideUp(500);
    } else {
        jQuery('#rocketmeluncur').slideDown(500);
    }
    var ftrocketmeluncur = jQuery("#ft")[0] ? jQuery("#ft")[0] : jQuery(document.body)[0];
    var scrolltoprocketmeluncur = $('rocketmeluncur');
    var viewPortHeightrocketmeluncur = parseInt(document.documentElement.clientHeight);
    var scrollHeightrocketmeluncur = parseInt(document.body.getBoundingClientRect().top);
    var basewrocketmeluncur = parseInt(ftrocketmeluncur.clientWidth);
    var swrocketmeluncur = scrolltoprocketmeluncur.clientWidth;
    if (basewrocketmeluncur < 1000) {
        var leftrocketmeluncur = parseInt(ftrocketmeluncur.offsetLeft);
        leftrocketmeluncur = leftrocketmeluncur < swrocketmeluncur ? leftrocketmeluncur * 2 - swrocketmeluncur : leftrocketmeluncur;
        scrolltoprocketmeluncur.css('left', (basewrocketmeluncur + leftrocketmeluncur + "px"));
    } else {
        scrolltoprocketmeluncur.css('left', 'auto');
        scrolltoprocketmeluncur.css('right', '10px');
    }
});

jQuery('#rocketmeluncur').click(function() {
    jQuery("html, body").animate({
        scrollTop: '0px',
        display: 'none'
    }, {
        duration: 600,
        easing: 'linear'
    });

    var self = this;
    this.className += ' ' + "launchrocket";
    setTimeout(function() {
        self.className = 'showrocket';
    }, 800);
});