diff --git a/src/client/app/desktop/views/components/user-preview.vue b/src/client/app/desktop/views/components/user-preview.vue
index 7ef8dff5be..1e1755ec3c 100644
--- a/src/client/app/desktop/views/components/user-preview.vue
+++ b/src/client/app/desktop/views/components/user-preview.vue
@@ -48,7 +48,7 @@ export default Vue.extend({
 				this.open();
 			});
 		} else {
-			const query = this.user[0] == '@' ?
+			const query = this.user.startsWith('@') ?
 				parseAcct(this.user.substr(1)) :
 				{ userId: this.user };
 
diff --git a/src/mfm/parse/core/syntax-highlighter.ts b/src/mfm/parse/core/syntax-highlighter.ts
index 3fb7a3b73d..2b13608d2b 100644
--- a/src/mfm/parse/core/syntax-highlighter.ts
+++ b/src/mfm/parse/core/syntax-highlighter.ts
@@ -197,7 +197,7 @@ const elements: Element[] = [
 
 		if (thisIsNotARegexp) return null;
 		if (regexp == '') return null;
-		if (regexp[0] == ' ' && regexp[regexp.length - 1] == ' ') return null;
+		if (regexp.startsWith(' ') && regexp.endsWith(' ')) return null;
 
 		return {
 			html: `<span class="regexp">/${escape(regexp)}/</span>`,
diff --git a/src/mfm/parse/elements/hashtag.ts b/src/mfm/parse/elements/hashtag.ts
index 129041774f..f4b6a78fa8 100644
--- a/src/mfm/parse/elements/hashtag.ts
+++ b/src/mfm/parse/elements/hashtag.ts
@@ -10,7 +10,7 @@ export type TextElementHashtag = {
 
 export default function(text: string, i: number) {
 	if (!(/^\s#[^\s]+/.test(text) || (i == 0 && /^#[^\s]+/.test(text)))) return null;
-	const isHead = text[0] == '#';
+	const isHead = text.startsWith('#');
 	const hashtag = text.match(/^\s?#[^\s]+/)[0];
 	const res: any[] = !isHead ? [{
 		type: 'text',
diff --git a/src/mfm/parse/elements/link.ts b/src/mfm/parse/elements/link.ts
index b353aebc5c..796aeb1ab3 100644
--- a/src/mfm/parse/elements/link.ts
+++ b/src/mfm/parse/elements/link.ts
@@ -13,7 +13,7 @@ export type TextElementLink = {
 export default function(text: string) {
 	const match = text.match(/^\??\[([^\[\]]+?)\]\((https?:\/\/[\w\/:%#@\$&\?!\(\)\[\]~\.=\+\-]+?)\)/);
 	if (!match) return null;
-	const silent = text[0] == '?';
+	const silent = text.startsWith('?');
 	const link = match[0];
 	const title = match[1];
 	const url = match[2];
diff --git a/src/misc/fa.ts b/src/misc/fa.ts
index 077bb51e6d..8be06362c3 100644
--- a/src/misc/fa.ts
+++ b/src/misc/fa.ts
@@ -25,9 +25,9 @@ export const replacement = (match: string, key: string) => {
 				arg == 'S' ? 'fas' :
 				arg == 'B' ? 'fab' :
 				'';
-		} else if (arg[0] == '.') {
+		} else if (arg.startsWith('.')) {
 			classes.push('fa-' + arg.substr(1));
-		} else if (arg[0] == '-') {
+		} else if (arg.startsWith('-')) {
 			transform = arg.substr(1).split('|').join(' ');
 		} else {
 			name = arg;
diff --git a/src/server/api/common/is-native-token.ts b/src/server/api/common/is-native-token.ts
index 0769a4812e..6afbc99ab5 100644
--- a/src/server/api/common/is-native-token.ts
+++ b/src/server/api/common/is-native-token.ts
@@ -1 +1 @@
-export default (token: string) => token[0] == '!';
+export default (token: string) => token.startsWith('!');
diff --git a/webpack/i18n.ts b/webpack/i18n.ts
index f73af72584..4fd439d1d5 100644
--- a/webpack/i18n.ts
+++ b/webpack/i18n.ts
@@ -8,7 +8,7 @@ export const replacement = (ctx: any, _: any, key: string) => {
 	const client = '/src/client/app/';
 	let name = null;
 
-	if (key[0] == '@') {
+	if (key.startsWith('@')) {
 		name = ctx.src.substr(ctx.src.indexOf(client) + client.length);
 		key = key.substr(1);
 	}