1 | function debounce(function_, wait = 100, options = {}) {
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2 | if (typeof function_ !== 'function') {
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3 | throw new TypeError(`Expected the first parameter to be a function, got \`${typeof function_}\`.`);
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4 | }
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5 |
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6 | if (wait < 0) {
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7 | throw new RangeError('`wait` must not be negative.');
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8 | }
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9 |
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10 |
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11 | const {immediate} = typeof options === 'boolean' ? {immediate: options} : options;
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12 |
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13 | let storedContext;
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14 | let storedArguments;
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15 | let timeoutId;
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16 | let timestamp;
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17 | let result;
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18 |
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19 | function later() {
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20 | const last = Date.now() - timestamp;
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21 |
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22 | if (last < wait && last >= 0) {
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23 | timeoutId = setTimeout(later, wait - last);
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24 | } else {
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25 | timeoutId = undefined;
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26 |
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27 | if (!immediate) {
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28 | const callContext = storedContext;
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29 | const callArguments = storedArguments;
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30 | storedContext = undefined;
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31 | storedArguments = undefined;
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32 | result = function_.apply(callContext, callArguments);
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33 | }
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34 | }
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35 | }
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36 |
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37 | const debounced = function (...arguments_) {
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38 | if (storedContext && this !== storedContext) {
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39 | throw new Error('Debounced method called with different contexts.');
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40 | }
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41 |
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42 | storedContext = this;
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43 | storedArguments = arguments_;
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44 | timestamp = Date.now();
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45 |
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46 | const callNow = immediate && !timeoutId;
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47 |
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48 | if (!timeoutId) {
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49 | timeoutId = setTimeout(later, wait);
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50 | }
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51 |
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52 | if (callNow) {
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53 | const callContext = storedContext;
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54 | const callArguments = storedArguments;
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55 | storedContext = undefined;
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56 | storedArguments = undefined;
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57 | result = function_.apply(callContext, callArguments);
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58 | }
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59 |
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60 | return result;
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61 | };
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62 |
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63 | debounced.clear = () => {
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64 | if (!timeoutId) {
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65 | return;
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66 | }
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67 |
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68 | clearTimeout(timeoutId);
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69 | timeoutId = undefined;
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70 | };
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71 |
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72 | debounced.flush = () => {
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73 | if (!timeoutId) {
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74 | return;
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75 | }
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76 |
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77 | const callContext = storedContext;
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78 | const callArguments = storedArguments;
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79 | storedContext = undefined;
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80 | storedArguments = undefined;
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81 | result = function_.apply(callContext, callArguments);
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82 |
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83 | clearTimeout(timeoutId);
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84 | timeoutId = undefined;
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85 | };
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86 |
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87 | return debounced;
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88 | }
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89 |
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90 |
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91 | module.exports.debounce = debounce;
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92 |
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93 | module.exports = debounce;
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