Question

在用j Query一号手法进行编造时,我发现以下代码:

[0, 0].sort(function()
{
    baseHasDuplicate = false;
    return 0;
});

By my understanding of javascript this code will sort array containing two zeroes with comparison function that will always set a global variable and will return equality, which has same effect as baseHasDuplicate = false;.
Coming from a valued source I think I missed something. Did I miss something or is this a programming fail?

Answer 1

参看here(chinese),该代码可用于测试 Chrome。 www.un.org/Depts/DGACM/index_french.htm

正如该条所解释的, happen优化了“.sort(......)”方法,使“代码”[0、0]sort(......)呼吁t履行特定的比较职能。

从该条来看,“.sort(......)”的 Chrome执行就是:

function sort(comparefn) {
  var custom_compare = (typeof(comparefn) ===  function );
  function Compare(x,y) {
    if (x === y) return 0;
    if (custom_compare) {
      return comparefn.call(null, x, y);
    }
    ...
}

由于0 ==0 是真实的,它赢得了t打comparefn。

在j Query一案中,它赢得了全球变量代码至false。

<>strong>EDIT: Sizzle s source Code, here,例如(在称为“Sizzle CSS 选择性发动机”的黄色部分上,请参看以下解释:

var chunker = /((?:((?:([^()]+)|[^()]+)+)|[(?:[[^[]]*]|[ "][^ "]*[ "]|[^[] "]+)+]|\.|[^ >+~,([\]+)+|[>+~])(s*,s*)?((?:.|
|
)*)/g,
        done = 0,
        toString = Object.prototype.toString,
        hasDuplicate = false,
        baseHasDuplicate = true;

// Here we check if the JavaScript engine is using some sort of
// optimization where it does not always call our comparision
// function. If that is the case, discard the hasDuplicate value.
//   Thus far that includes Google Chrome.
[0, 0].sort(function(){
        baseHasDuplicate = false;
        return 0;
});

Look。

友情链接