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The variable delete declared through var cannot be deleted, but it is also a property of window? Seek to explain
var foo = 1; window.bar = 2; delete foo; delete bar; console.log(window.foo,window.bar)//1 undefined
光阴似箭催人老，日月如移越少年。
Because the variable declared withvarhas the attributeconfigurable = false, so it cannot be deleted.
var
configurable = false
var ss = 0; console.log(Object.getOwnPropertyDescriptor(window, 'ss')); /* { configurable: false enumerable: true value: 0 writable: true } */
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Because the variable declared with
varhas the attributeconfigurable = false, so it cannot be deleted.