would （just） as soon do something as look at you 为习语。意为某人想要做对你有害的事情。

英语的有些比较结构随着语言的发展演变已经成了一种习语，例如 as well as 作为准并列连词，as long as 作为引导条件状语从句的复合连词，as/so far as sb/sth is concerned 等.  同理，would just as soon... as... 也是一种习语性用法。

《韦氏高阶》在 soon 的词条下给出了下面习语：

would sooner or would just as soon

— used to indicate what you want or prefer to do, have, etc.

He would sooner [=would rather] lose everything than admit that he was wrong.

We asked him to come with us, but he said he'd just as soon stay home.

我们可以看出，该词典把would sooner 和 would just as soon 视为同义结构，而would sooner 等于 would rather. 意为“宁愿、宁可”做某事。如果想要表示出与什么相比而宁愿做某事，则可以用than和as 与 would sooner 和 would just as soon 呼应，构成择比结构：would sooner do A than do B; would just as soon do A as do B. 宁可做A事，也不做B事。在这种结构中，sooner... than 以及 just as soon... as 起准并列连词作用，do A 和 do B是并列的二项，都是情态动词would后的不带to的不定式（不宜称为动词原型）。我们对下面词典例句做一个转换，说明其用法和意义。

We asked him to come with us, but he said he'd just as soon stay home.

He'd just as soon stay home as come with us.

He'd sooner stay home than come with us.

He'd rather stay home than come with us.

He'd stay home rather than come with us.

He'd stay home sooner than come with us. (使用较少）

He'd stay home as soon as come with us. （使用较少）

当would just as soon ... as 后为look at someone 的时候，则又是一个固定习语，do A 一定表示的是对你加害之类的坏事，do B 固定为look at sb. 翻译为汉语时，通常不翻译look at sb这部分。例如：

He would just as soon kill you as look at you. 他会杀了你的。

You want me to trust his sort? He would just as soon cheat you as look at you. 你想让我相信他那号人?他根本就不把骗人当作一回事。

He would just as soon offend other people as look at them 他根本就不把得罪人当回事。

just可以省略，as soon可以移至第一个不定式之后。例如

And he said some of these guys would kill you as soon as look at you. 他说这些人会杀了你的。

It's the worst kind of killer that would shoot a man in the back just as soon as look at him. 只有最糟糕的杀手才会从背后开枪。

网友提问的句子就是最后这种用法，would kill you as soon as look at you = would just as soon kill you as look at you.  注意这里as soon as 并不是引导时间状语从句的复合连词，不能理解为“一看到你就会杀你”。look at you不是动词原型，而是不带to的不定式。翻译时不翻look at you。