为什么这个Javascript插件在移动设备上使用“touchstart”而不是“click”事件

在JavaScript插件中，我发现了以下函数：

function mobilecheck() {
    var check = false;
    (function(a){if(/(android|ipad|playbook|silk|bb'd+|meego).+mobile|avantgo|bada'/|blackberry|blazer|compal|elaine|fennec|hiptop|iemobile|ip(hone|od)|iris|kindle|lge |maemo|midp|mmp|netfront|opera m(ob|in)i|palm( os)?|phone|p(ixi|re)'/|plucker|pocket|psp|series(4|6)0|symbian|treo|up'.(browser|link)|vodafone|wap|windows (ce|phone)|xda|xiino/i.test(a)||/1207|6310|6590|3gso|4thp|50[1-6]i|770s|802s|a wa|abac|ac(er|oo|s'-)|ai(ko|rn)|al(av|ca|co)|amoi|an(ex|ny|yw)|aptu|ar(ch|go)|as(te|us)|attw|au(di|'-m|r |s )|avan|be(ck|ll|nq)|bi(lb|rd)|bl(ac|az)|br(e|v)w|bumb|bw'-(n|u)|c55'/|capi|ccwa|cdm'-|cell|chtm|cldc|cmd'-|co(mp|nd)|craw|da(it|ll|ng)|dbte|dc'-s|devi|dica|dmob|do(c|p)o|ds(12|'-d)|el(49|ai)|em(l2|ul)|er(ic|k0)|esl8|ez([4-7]0|os|wa|ze)|fetc|fly('-|_)|g1 u|g560|gene|gf'-5|g'-mo|go('.w|od)|gr(ad|un)|haie|hcit|hd'-(m|p|t)|hei'-|hi(pt|ta)|hp( i|ip)|hs'-c|ht(c('-| |_|a|g|p|s|t)|tp)|hu(aw|tc)|i'-(20|go|ma)|i230|iac( |'-|'/)|ibro|idea|ig01|ikom|im1k|inno|ipaq|iris|ja(t|v)a|jbro|jemu|jigs|kddi|keji|kgt( |'/)|klon|kpt |kwc'-|kyo(c|k)|le(no|xi)|lg( g|'/(k|l|u)|50|54|'-[a-w])|libw|lynx|m1'-w|m3ga|m50'/|ma(te|ui|xo)|mc(01|21|ca)|m'-cr|me(rc|ri)|mi(o8|oa|ts)|mmef|mo(01|02|bi|de|do|t('-| |o|v)|zz)|mt(50|p1|v )|mwbp|mywa|n10[0-2]|n20[2-3]|n30(0|2)|n50(0|2|5)|n7(0(0|1)|10)|ne((c|m)'-|on|tf|wf|wg|wt)|nok(6|i)|nzph|o2im|op(ti|wv)|oran|owg1|p800|pan(a|d|t)|pdxg|pg(13|'-([1-8]|c))|phil|pire|pl(ay|uc)|pn'-2|po(ck|rt|se)|prox|psio|pt'-g|qa'-a|qc(07|12|21|32|60|'-[2-7]|i'-)|qtek|r380|r600|raks|rim9|ro(ve|zo)|s55'/|sa(ge|ma|mm|ms|ny|va)|sc(01|h'-|oo|p'-)|sdk'/|se(c('-|0|1)|47|mc|nd|ri)|sgh'-|shar|sie('-|m)|sk'-0|sl(45|id)|sm(al|ar|b3|it|t5)|so(ft|ny)|sp(01|h'-|v'-|v )|sy(01|mb)|t2(18|50)|t6(00|10|18)|ta(gt|lk)|tcl'-|tdg'-|tel(i|m)|tim'-|t'-mo|to(pl|sh)|ts(70|m'-|m3|m5)|tx'-9|up('.b|g1|si)|utst|v400|v750|veri|vi(rg|te)|vk(40|5[0-3]|'-v)|vm40|voda|vulc|vx(52|53|60|61|70|80|81|83|85|98)|w3c('-| )|webc|whit|wi(g |nc|nw)|wmlb|wonu|x700|yas'-|your|zeto|zte'-/i.test(a.substr(0,4)))check = true})(navigator.userAgent||navigator.vendor||window.opera);
    return check;
}

并用字母将此代码eventtype = mobilecheck() ? 'touchstart' : 'click';
据我了解，此插件首先检查移动设备，然后根据结果将touchstart或click分配给eventtype。

好吧，我的问题为什么我们进行事件检查，即使点击事件也与移动设备中的触摸启动相同。

更清楚的是，如果我用这行eventtype = 'click';替换上述所有代码会发生什么，该插件将在移动设备中正常工作。