Jaw-dropping JavaScript tricks

Read a JavaScript technique today and learn and collect
1. Quickly print a scoring situation with a five-point system function getrating (rating) {if (Rating > 5 | | Rating < 0) throw new Error (' number not in range '); Return ' ★★★★★☆☆☆☆☆ '. substring (5-rating, 10-rating); }
2. Splice repeating string (ABCABCABC)//output n ' abc ' concatenation of the string var str = new Array (n+1). Join (' abc ');

• False = =! []
• true =!! []
• undefined = [][[]]
• NaN = +[![]]
• 0 = +[]
• 1 = +!+[]
• 2 =!+[]+!+[]
• Ten = [+!+[]]+[+[]]
• Array = []
• Number = +[]
• String = []+[]
• Boolean =! []
• Function = [[] [filter]
• eval = [] [filter] ["constructor"] (CODE) ()
• window = [] [filter] ["constructor"] ("return This") ()
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Jaw-dropping JavaScript tricks