Uncaught SyntaxError: Unexpected

var c = "[{'mid':'28275','url':'\/static\/image\/realNameImage\/2020\/January\/7\/A30gdmb2_750X1000.png'}, {'mid':'28275','url':'\/static\/image\/realNameImage\/2020\/January\/7\/A30gdmb2_750X1000.png'}]"

console.log(JSON.parse(c))

一看这代码完全是没毛病，可是总有意想不到的红色出现；
Uncaught SyntaxError: Unexpected token ' in JSON at position 2 at JSON.parse (<anonymous>) at <anonymous>:1:18

image.png

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可是我这样一操作，又没毛病了；

var c = '[{"cid":"28275","url":"\/static\/image\/realNameImage\/2020\/January\/7\/5wMUlxsZ_750X1000.png"},{"cid":"28275","url":"\/static\/image\/realNameImage\/2020\/January\/7\/PE4ju0oT_750X1000.png"}]'

console.log(JSON.parse(c))

又正常了，fuck，why？；

image.png

这是啥原因？