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) //zachAnother unreasonable var scenario is that the loop variable used to count is leaked as a global variable, as shown in the following example:var a = [];for (var010; i++) { function () { console.log(i); };}a[6// 10In the above code, the variable i is declared Var and is valid at the global scope. So each cycle, the new I value will overwrite the old value, resulting in the final output of the last round of the I value. With let, this problem does not occur.var a = [];for (let010; i++

}console.log(name) //zachAnother unreasonable var scenario is that the loop variable used to count is leaked as a global variable, as shown in the following example:var a = [];for (var i = 0; i 10; i++) { a[i] = function () { console.log(i); };}a[6](); // 10In the above code, the variable i is declared Var and is valid at the global Scope. So each cycle, the new I value will overwrite the old value, resulting in the final output of the last round of the I Value. With let, This problem does not o

variable it declares to be valid only let within the code block where the command resides.let name = ‘zach‘while (true) { let name = ‘obama‘ console.log(name) //obama break}console.log(name) //zachAnother unreasonable var scenario is that the loop variable used to count is leaked as a global variable, as shown in the following example:var a = [];for (var i = 0; i 10; i++) { a[i] = function () { console.log(i); };}a[6](); // 10In the above code, the variable i is declared Var and is valid at

unreasonable scenarios. The first scenario is that the inner variables you see now cover the outer variables. Let, in effect, adds a block-level scope to JavaScript. Use the variable it declares to be valid only within the block of code where the Let command is located. Another unreasonable scenario that Var brings is that the loop variable used to count is leaked as a global variable, see the following example: var a = []; for (var i = 0; i In the code above, the variable i is declared by VA

scenario is that the cyclic variables used to count are leaked as global variables. See the following example: var a = []; for (var i = 0; i In the code above, variable I is declared by VAR and is valid globally. Therefore, in each loop, the new I value will overwrite the old value, resulting in the final output of the last round of I value. Using let will not cause this problem. var a = []; for (let i = 0; i Let's look at a more common example to learn how to solve this problem with closur