课程: Mastering Web Developer Interview Code
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How would you use JavaScript reduce()?
- [Narrator] Reduce is a higher order function just like the map method we covered in the previous week. Now it's the sign to solve a common problem going over a list of elements and retrieving a single value related to them as the result. So let's take a look at how we would do that with traditional JavaScript. So you probably create something like a variable to hold a running total and then you will create some sort of array to hold the list of elements you want to go through. And then you would use perhaps something like a for loop to iterate through those different array items so you would maybe take that total value and continue to add the values of each of the elements in the array. This is a little bit messy and map is designed to solve this problem. That is a very common pattern in JavaScript. So let's take a look at how that looks with reduce. Now, reducing we'll take a callback where you can pass along a…
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How do you use the data- attribute in HTML?11 分钟 14 秒
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Are you comfortable using jQuery?11 分钟 32 秒
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Describe when you should use the bind() method5 分钟 21 秒
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Do you know how to use the conditional operator?3 分钟 43 秒
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Have you used Ajax to load an external file?8 分钟 25 秒
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Have you used JavaScript templates?7 分钟 3 秒
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How do you manipulate the DOM?11 分钟 7 秒
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How do you search using functional programming?6 分钟 27 秒
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How do you use a constructor to create instances?10 分钟 33 秒
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How do you use arrow functions in ES6?6 分钟 30 秒
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How do you use the Fetch API?7 分钟 22 秒
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How do you render JSON to a DOM element?9 分钟 36 秒
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How does an IIFE work?7 分钟 12 秒
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How does immutability work in JavaScript?4 分钟 12 秒
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How would you use JavaScript reduce()?3 分钟 54 秒
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Quick concepts: Do you have experience linting your code?2 分钟 31 秒
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What are event bubbling and propagation about?11 分钟 42 秒
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What does "use strict" do?3 分钟 28 秒
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What is a callback and how do you use it?8 分钟 51 秒
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What is the relationship between promises and callbacks?9 分钟 57 秒
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What is the virtual DOM?7 分钟 7 秒
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What is variable hoisting and how do you guard against it?8 分钟 43 秒
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What tooling options have you used in the past?7 分钟 11 秒
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When would you use recursion?6 分钟 25 秒
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Can you build a Sass mixin?7 分钟 57 秒
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Do you know how to use CSS variables?10 分钟 38 秒
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Animate an underline on hover in CSS9 分钟 48 秒
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Explain the difference between absolute and relative positioning7 分钟 55 秒
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How comfortable are you with Sass?12 分钟 10 秒
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How do you animate CSS?9 分钟 41 秒
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How do you debug CSS using your browser?10 分钟 47 秒
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How do you use calc() in CSS?9 分钟 56 秒
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How would you use flexbox to control horizontal alignment?7 分钟 21 秒
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In CSS, what's the difference between ems and rems?9 分钟 58 秒
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What's the difference between a pseudo-class and a pseudo-element?6 分钟 16 秒
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Do you know how to use npm?8 分钟 40 秒
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Do you have experience using version control?16 分钟 37 秒
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How does routing work in a modern web application?9 分钟 30 秒
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